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82 Unequilibrated Ordinary Chondrites: Planetochemistry and Mineralogy

Last Updated: 20th May 2017

By Lon Clay Hill

Full Title: Mineralogical Inventories of 82 Unequilibrated Ordinary Chondrites: A Preliminary Survey from an explicitly Planetological (Planetochemical) Perspective

Lon Clay Hill, Jr. (retired)

Abstract

A Preliminary Survey of Mineralogical Inventories for 82 unequilibrated ordinary chondrites (UOCs) is presented. The 82 meteorite hosts include all 47 witnessed falls recognized with unique names by the Meteoritical Society as well as an additional 35 selected finds recovered after their unrecorded arrivals. We pursue — in particular — the frequency and pattern of distribution for 94 minerals and mineralites (mineral groups, IMA minerals, mineral varieties, and other mineralogically significant items) which have been reported for the meteorites at Mindat (=mindat.org). Major topics of discussion are the varieties of pyroxenes, anomalies in feldspar and plagioclase varieties, weathering effects, singular occurrences, and the adequacy of the currently readily available research literature. An underlying thematic of the author's approach is the attempt to use a mineralogical terminology which is transparent to the planetary genetic significance of meteoritic minerals. More explicitly, the author's preliminary assumption is that specific episodes recorded in every mineral of every meteorite provide us with additional — and possibly dispositive — information about the putative ancient asteroidal homes or formational nebular environments of many or all ordinary chondrites.

The format is explicitly modular with an Introduction followed by three major Sections containing Meteorite descriptions, Minerals and Mineralites data, and Planetochemical and Mineralogical context, respectively. Section IV, in particular, provides both a simultaneous and more general description of UOC mineralogy which, by necessity, amplifies previously introduced Section III material. Three 'Tables' highlite the foundational data of Sections II,III and IV with immediate links to additional technical meteoritical and mineralogical data and references. The Tables themselves, however, are embedded within a more deliberate and slower moving text which is simultaneously both epistemological and pedagogical. A very brief Summary, Bibliography, and Appendix follow the 4 primary Sections.

Linguistic Caveat: In the meteoritic literature mineralogically important phases (mineralites) are often described using chemically defined terms which suppress distinctions that are de rigueur in most formal mineralogical and geological forums. In the Appendix, we list some terminological distinctions, conventions, or refinements intended to make both chemical and mineralogical characteristics of meteoritic phases and aggregates more explicit and more transparent in scientific discussions. Important neologisms plus carefully defined and/or redefined terms include mineralite, planetochemical, Fe-Ni metal, kamacite, and enstatite. In addition, the author often simplifies the spelling of words with relic gutturals which have not been used in common English speech since the end of the 1st millennium of the common era.



Section I : Introductions — Ordinary Chondrites, Unequilibrated Ordinary Chondrites, and Their Mineralites


Full Section Title: Introductions — Ordinary Chondrites (OC); Unequilibrated Ordinary Chondrites (UOC); Their Mineralites (Minerals, Mineral Groups and Varieties, Chemically Defined Phases); The Present StudyIntroduction IA: The Ordinary Chondrites (Overall Context)

The ordinary chondrites (OCs) constitute a large fraction (75-80%) of all meteorite falls and a comparable percentage of finds (meteorites recovered subsequently to their unrecorded falls). The unequilibrated ordinary chondrites (UOCs) are a small subset of the ordinary chondrites accounting for at least 5% of all recovered ordinary chondrites. Two caveats: (I) 'Exact' statistics can be misleading as a number of falls and an even higher percentage of finds have been either incompletely or even poorly classified; (II) A significantly large, but poorly quantifiable number of meteorite finds recovered from the Antarctic ice and African desserts are small fragments of large meteorites or meteorite showers which have been separated from the other meteorite stones which reached the earth at the 'same' time (i.e., to within a few minutes of each other). These meteorite fragments of the same 'fall' have been separated by natural processes (fragmentation within the earth's atmosphere, breakage and movements induced by rain, floods, and ice flow). In addition, especially in some commercial venues, meteorites may be separated by human vendors who vendor fragments of the same original fall as individual meteorites. Before proceeding to the mineralogical thematics of our discussion, however, it will be helpful to make two additional definitions about the ordinary chondrites. The olivine and pyroxene in most ordinary chondrites is relatively equilibrated — specifically, most of the olivine in such a meteorite is of uniform composition and the Ca-poor pyroxene is either compositionally uniform or nearly so. Based upon the degree of equilibration these 'equilibrated ordinary chondrites' (EOC) are routinely assigned to petrologic types 4 thru 6, and, very rarely, to type 6/7 or 7. In similar fashion, the unequilibrated ordinary chondrites are assigned petrologic types 3.00—3.9. An additional definitional caveat — all ordinary chondrites are believed to have begun as unequilibrated assemblages of minerals of diverse origins and composition which were subsequently compacted together and 'reequilibrated' to various levels of equilibrium and uniformity. Associated, then, with any overall relatively uniform level of 'equilibration' one can expect some level of relic inhomogeneities and disequilibrium in almost any ordinary chondrite.

With these caveats and some additional remarks below we will eventually discuss the scientific pertinence of the minerals found in the unequilibrated ordinary chondrites (meteorites classified as belonging to the H3, H/L3, L3, L/LL3, and LL3 petrologic types). The main defining characteristic of the UOCs is that — unlike the great majority of ordinary chondrites — the unequilibrated ordinary chondrites were less thermally metamorphosed during the compaction process(es). Consequently, while the major silicates (olivine, pyroxenes, and plagioclase feldspar) of the chondrules and matrix of ordinary chondrites are of more or less uniform composition, the olivine, pyroxene, and feldspar of unequilibrated ordinary chondrites is decidedly variable. More generally, the mineralogy of unequilibrated ordinary chondrites is characterized by a remarkable mineralogical diversity which includes rare and unusual phases of diverse or even unknown provenance. Some of the genetic implications of this mineralogical diversity will unfold as we proceed, but we provide one example for starters. In a number of the unequilibrated ordinary chondrites we find tiny relics of pre-solar mineralites: 'Stardust' — minerals and phases with the elemental and isotopic signatures of supernovae ejecta and red giant outflow from long dead stars that contributed some of the ingredients to the ancient star cloud which produced the the ancient Solar Nebula out of which the sun, the earth, and the entire Solar System were born.

We note that we have begun our inquiry by providing that some technical definitions that are entangled with some decidedly 'Big Picture' considerations. Good science often proceeds when researchers utilize their 'Big Picture' beliefs, hunches, and convictions implicitly or even unconsciously as they focus on the issues at hand. In this case, however, the author believes that recent historical developments in both meteoritics and mineralogy have been accompanied by some disciplinary-specific linguistic developments which are both opaque and inconsistent with overall scientific clarity. Our procedure here will be to try to anchor the descriptive and informational material of our three Tables (The Meteorites, The Minerals, The Minerals-&-their-Cohorts) with explanatory text — as well an accompanying terminological Appendix. For now however, we first discuss the mineralogy and genesis of all ordinary chondrites. This provides a more natural context for our primary focus on the relationship between the 94 mineralites highlighted here and their 82 unequilibrated ordinary chondrite hosts.

The ordinary chondrites constitute a clearly definable subset of meteorites. Texturally, they are defined by the presence of chondrules, roughly spheroidal silicate-rich grains, or clear evidence of the previous presence of such chondrules. The chondrules are found within a matrix of silicates, sulfides, and Fe-Ni metal. Mineralogically, the relatively unshocked ordinary chondrites are characterized by the dominance of Mg-rich olivine and pyroxene accompanied by lesser amounts of kamacite, taenite, troilite, albitic plagioclase, minor diopsidic clinopyroxene, and some common accessories (vide infra). As a general rule, ordinary chondrites almost always contain some tiny or large amount of glassy material produced by impacts during accretion or in subsequent epochs. These impacts alter the mineralogy in various ways — in particular much or even all of the plagioclase feldspar within a meteorite may have been altered into maskelynite before its arrival on the planet earth. Shocked or unshocked, however, all ordinary chondrite falls large enough to provide a grossly representative sample are characterized by a distinctive range of silicate compositions, oxygen isotope ratios, and bulk iron content sufficient to distinguish them form all other meteorite groups (e.g., carbonaceous chondrites, Martian meteorites, etc.). The ensemble of ordinary chondrites can be further subdivided into three major groups — the H, L, and LL ordinary chondrites that are relatively high, low, or very low in total iron, respectively. Associated with the overall iron content is a strong correlation between the overall degree of oxidation of the meteorite and increasing bulk iron content (Prior's rule). Thus, paradoxically, the amount of free or unoxidized Fe-Ni metal decreases with overall bulk iron content because the silicates contain a higher fraction of that oxidized iron. Practically speaking, this means that the iron content of the olivine (mol% fayalite) and Ca-poor pyroxene (mol% ferrosilite) are so tightly correlated with the overall bulk iron content that one can — usually — generate a reliable classification into one of the major ordinary chondrite groups utilizing only a small thin section of the meteorite. Related to the relative ease of oxidation of iron, nickel, and cobalt one may also use the Fe/Co ratio in kamacite as a proxy indicator of ordinary chondrite (OC) classification. Summarizing these and some additional statistical and chemical considerations, we might further conclude that the bulk iron, oxygen isotopes, olivine and Ca-poor pyroxene compositions, and Co content of kamacite of ordinary chondrites are tightly correlated in a way that suggests that they constitute three naturally separate groups. Originally formed, one might suggest, in three separate places or, even, on three separate homeworlds.

And, indeed, I — and many others — believe that it is more than likely that ordinary chondrites are, in the main, fragments of three distinct asteroidal bodies that were once members of the asteroid belt. You may occasionally run into the statement or suggestion that all ordinary chondrites are derived from 3 original parent bodies (OPBs), but that overstates the case. More accurate, I think, is the perspective that there is an apparent tendency for ordinary chondrites to have properties that would be most simply explained if they had originated in three original parent bodies. Whether three such putative OPBs can actually accounted for all or most characteristics of the entire ordinary chondrite clan is yet to be determined. The first problem with such this hypothesis we must mention is that that while bulk chemistry, isotope ratios, and mineralogical compositions in OCs are tightly correlated, they are not perfectly correlated. Also, the precise boundaries of our classification boundaries are a little fuzzy. In particular, there are number of ordinary chondrites whose properties are intermediate between those of the 3 major groups — the H/L chondrites and the L/LL chondrites have physical characteristics intermediate between the H and L chondrites and between the L and LL chondrites, respectively. The possible causes of these fuzzy boundaries and intermediate classifications are many. First, it could be simply that the range of physical properties on the original parent bodies overlapped each other. One might also consider the possibility that sampling errors in our small and locally variegated specimens blur the overall distinguishing characteristics of the original parent bodies. Or, there may have been significant exchanges of material in the region where the original asteroidal homes accreted or in collisions between large fragments of these OPBs after disruption. And this brings us to the central importance of the unequilibrated ordinary chondrites (UOCs) and their mineralogical diversity. The enormous variety of UOC minerals and mineralites bespeak an enormous range of physical conditions embodied in the planetismal aggregates destined to become (putative) homeworlds of the ordinary chondrites.

Introduction IB: The Unequilibrated Ordinary Chondrites (UOCs)

The Unequilibrated Ordinary Chondrites (UOCs) — roughly 5-10% of all ordinary chondrites — are physical assemblages whose overall chemistry and isotopic ratios, formational history, and subsequent collisional histories can be most easily understood as a consequence of an ancient origin on the putative original parent bodies (OPBs) of the much more numerous equilibrated ordinary chondrites (EOCs). More generically speaking, the shared overall physical characteristics of all ordinary chondrites bespeak an origination within a common physical environment in the early solar nebula ~4.5—4.6 Ga before the present. Mineralogically speaking, the UOCs are most readily differentiated by the lack of overall equilibrium within the olivine and pyroxenes which mineralogically dominate the constituents of all ordinary chondrites. Associated with this most readily observed disequilibrium are several other features within theses meteorites which are usually observed. We note 3 of them here: (A) Ca-poor pyroxenes in UOCs are usually clinopyroxenes; (B) Feldspar grains are often tiny and difficult to characterize mineralogically; (C) Primary glass is present in UOCs. The extent of these mineralogical gradations are embodied in the petrologic subtypes assigned to the UOCs — Types 3.0-3.9. Critical to the present discussion is an overlying caveat — all ordinary chondrites are aggregates of once unequilibrated aggregates which may reach our planet with a mineralogical assemblage which can be assigned an (overall) level of metamorphically induced equilibrium of petrologic types 3.0 thru 6/7. However, as mentioned above, every ordinary chondrite has small and tiny regions or inclusions which represent disturbances and collisions which have interrupted any metamorphic equilibrium that may have been obtained at some time. Furthermore, by definition, the unequilibrated ordinary chondrites have experienced a minimum of such equilibrating processes. Thus, the major and minor inhomogeneities and idiosyncrasies which are found within various equilibrated ordinary meteorites abound within the unequilibrated ordinary chondrites. In this context the mineralogical diversity of the unequilibrated ordinary chondrites has special scientific relevance. Each mineral or mineralite represents at least one event or sequence of events in the history of the meteorite. These mineralites present us with new opportunities (1) to understand events that occurred during and before the formation of our solar system some 4.6-4.68 billion years ago and (2) to understand events that occurred during the formation of the asteroidal parent bodies (events whose mineralogical record have been largely erased in the EOCs).

Mineralogically speaking, in a sufficiently large and unweathered sample of an unequilibrated ordinary chondrite we would expect to find olivine, pyroxenes, and tiny feldspar grains within the silicates. While the overall composition of the primary silicates is more or less that found in all ordinary chondrites, we have learned not be surprised to find individual grains of exotic composition within chondrules and/or matrix. Thus, some of the olivine and pyroxene grains might be extremely Mg-rich — e.g., we frequently see forsterite, enstatite, and clinoenstatite sensu stricto [compositions Fo>90 mol%; En>90 mol%; En>90 mol%, respectively]. Likewise, in addition to the expected normative plagioclase (bytownite) or plagioclase glass (maskelynite), we also find end-member albite (An90-99), anorthite (Ab90-99) or K-rich orthoclase. Sulfides are pervasive, with troilite dominant, but occasional primary pyrrhotite, pentlandite, and other more oxidized (and reduced) sulfides are reported. Fe-Ni metal is also present. When found in small grains and droplets, both the Fe-Ni metal and the sulfides are often difficult or impossible to characterize them mineralogically. However, besides kamacite and taenite, we are not surprised to find martensite and plessite. Martensite (disordered kamacite) and plessite (a microscopic kamacite-taenite intergrowth) are apparent products of shock events and, for plessite, subsequent quick cooling which occurred either during accretion, during metamorphic epochs on an original parent body (OPB), or during subsequent collisions after ejection from the OPB.

Recapitulating and anticipating, we now summarize the central importance of the unequilibrated ordinary chondrites (UOCs) and their mineralogical diversity. The UOCs embody an enormous variety of minerals and mineralites which bespeak an enormous range of physical conditions which were embodied in the lithological aggregates which eventually became the putative homeworlds of the ordinary chondrites. Speaking rhetorically, it can be said that while one might reasonably argue that all or almost all of the equilibrated ordinary chondrites are derived from either two or three original parent bodies, the unequilibrated ordinary chondrites themselves make it quite clear that the two or three or more original parent bodies of the ordinary chondrites were derived from multiple and potentially distinguishable sources. The accretion of ordinary chondrites were fed by multiple streams of material.

The Present Study: Procedures and Protocols

According to the Meteoritical Bulletin Database, as of 22 April 2017, exactly 2784 meteoritical stones had been recognized as properly classified unequilibrated ordinary chondrites (UOCs) and given unique names. Our study discusses the mineralogy of all 47 recognized UOC falls and an additional 35 selected finds. The finds include all UOC finds highlighted in the Atlas of Meteorites (2015) and almost all UOC finds studied in Paul Ramdohr's The Opaque Minerals of Stony Meteorites (1973) ["Opaque Minerals"]. The overall coverage provided by this review is necessarily somewhat mixed. At one extreme are very small meteorites which have been given minimal mineralogical and petrographic coverage since their initial recognition. At the other extreme are large meteorites which have been studied extensively by various observers with numerous instruments. The advantage of the falls, of course, is that their interiors — if the meteorites have been curated properly — are characterized almost entirely by preterrestrial mineralogical assemblages. The advantage of the finds found in the Atlas of Meteorites is that they are presented within an overall research context that allows the interested reader to pursue the deeper implications of current research if he or she is up to the task. The advantage of the finds found in Ramdohr's Opaque Minerals is that Ramdohr's skilled use of oil-immersion microscopy allowed him to recognize a number of oxides and sulfides that are only occasionally recognized by other observers using only standard thin sections and electron microscopy techniques. A disadvantage of the finds, of course, is that terrestrial weathering alters the preterrestrial mineralogical assemblage. To partially compensate for these complication, the author has — when able — supplied additional information to help distinguish pre-terrestrial alterations of meteoritic assemblages from the weatherates due to post-terrestrial alterations. The author also explicitly uses some terminological conventions which allow for a more transparent utilization of important mineralogical-chemical relationships than is possible with terrestrially focused IMA conventions [which sometimes obscure essential planetological and cosmochemical distinctions]. Finally, the mineral inventories collected here are not complete. The information gathered here has been gleaned from the more readily available literature rather from an exhaustive search which would require more resources than the author possesses. There is, however, sufficient information available here to draw some tentative conclusions and, also, hopefully, enough information to help others to pursue further topics of interest inherent in this intriguing ensemble of meteorites.


Section II — 82 Unequilibrated Ordinary chondrites (UOCs)

Full Section Title: 82 UOCs (55 falls, 35 finds), their physical characteristics, mineral and mineralite tallies, Mindat terminology and protocols, planetological and planetochemical terminology and problematics

The 82 Unequilibrated Chondrites considered here include 47 Falls and 35 Finds. Seventy-seven of the meteorites belong to the three primary ordinary chondrite groups (31 H3, 23 L3, 23 LL3). While the 525 stones in the LL3 ensemble (19% of the UOCs listed by April 2017) is a much smaller group than the H3 and L3 ensemble, their provenance is a little more puzzling so we have elected to give the LL3 chondrites roughly equal prominence in our study. We also consider five meteorites of 2 'mixed' chondritic groups — 3 H/L3 meteorites and 2 L/LL3 chondrites. These 5 meteorites are of special interest as their physical characteristics are either (1) intermediate between two primary groups or (2) 'inconsistent' regarding two groups. Furthermore, the H/L3.6 Tieschitz chondrite is an unusually mineraliferous assemblage with 36 mineralites, including 27 IMA-defined minerals, reported here. Likewise, recovered masses for some meteorites are quite large (5 masses > 100 kg) while recovered masses for other meteorites are quite small (8 masses < 0.1 kg). The largest mass considered here is Northwest Africa 10214 (1000 kg); the smallest mass considered here is Piancaldoli (0.0131 kg). However, more interesting for our purposes are the variation in mineralite tallies. 30 or more mineralites have been recorded for 7 meteorites, all of them witnesses falls and 6 of them LL chondrites. Among the finds Moorabie, a highly shocked Australian chondrite (L3.8-an; S4-5), has the highest number of recorded mineralites (N= 26). On the other hand, less than 5 mineralites are reported for 8 meteorites, clearly an undesirable situation. While there is a moderate correlation between observed mineralites and meteorite mass (as reported here), the correlation is strikingly absent at times. 23 mineralites, including 15 IMA-defined minerals are cited for tiny Piancaldoli!

In Table A, then, we present our highlighted 82 ordinary chondrites. We note that immediate mindat.org links to additional information about each individual meteorite's location of the discovery, actual date of fall, and citations for every posted mineralite can be obtained by simply clinking on the meteorite name. An immediate additional link to the Meteoritical Bulletin Database for individual meteorites is usually found in the digital bibliography at the mindat.org location site for the meteorite. Readers who are unfamiliar with mindat.org ("Mindat") should realize that the Mindat 'Mineral List' for each meteorite highlites International Mineralogical Association (IMA) defined minerals, described as 'valid minerals'. Also prominent are other IMA-defined groups, subgroups, solid solution series, and varieties or 'mineralogical items'. However, in keeping with its own mission to serve a diverse constituency — amateurs, jewelers, mining engineers, teacher, and research scientists — the 'Mineral List' algorithms for listed meteorite recognizes a number of additional mineralogical terms which are not recognized by the IMA. These include a number of older terms as well as some generic and/or informal terms still in currency with various groups. All Mindat listable terms — formal or informal — are described as 'mineralogical items'. Two characteristics of the 'vocabulary' of the Mineral List are of particular interest to our inquiry:

First. While IMA-defined minerals are unique, other terms frequently overlap so that occasionally two different labels may be applied to the same physical aggregate (e.g., a meteorite may be described as having both 'pyroxene' and 'clinopyroxene'). In these instances — if one can — one needs to look 'under the label' — to see whether the descriptions are redundant (e.g., in this instance we might want to know if there are any indications of orthopyroxene in addition to the clinopyroxene. The author tries to reduce such redundancies, but these ambiguities are inherent in the Mindat format which allows uploads of diverse levels of mineralogical specificity by various parties.

Secondly. As would be expected in a mineralogically focused enterprise, Mindat algorithms normally exclude chemically defined or mixed chemically-mineralogically defined entities. One important exception is 'silica'. This term is frequently used — for example — in both mining and meteoritics for various mineralogical aggregates of silica-rich or, even, nearly pure silica mixtures of importance. However, in the meteoritics literature we find that chemically defined terms are ubiquitous. Ca-poor pyroxene, Ca-phosphate, silicon carbide (SiC) come immediately to mind. The author uses the term 'Mineralite' to include (1) all IMA-defined 'minerals' or 'mineral groupings', (2) all Mindat listable 'mineralogical items', (3) various assortae, and (4) mineralogically significant, but essentially chemically-defined physical aggregates important in planetochemically-laden meteoritic discourse. As the reader proceeds he/she will discover that planetochemical considerations — the utilization of chemical signatures to help determine the original solar system region of origin or homeworld (e.g., 'Original Planet Body' [OPB] for every meteorite — may be folded into our mineralogical discussions in even more explicit terms than is customary in much of the formal meteoritic literature.

Table A: 82 Unequilibrated Ordinary Chondrites [Primary Data]


COLUMNS
METEORITE — The meteorite's official name or abbreviation as listed at the Meteoritical Bulletin Database.
REGION — Country or Region of Discovery
KLASS — The meteorite's classification at the Meteoritical Bulletin Database. Additional Shock and Weathering levels usually from the Catalogue of Meteorites (5/e).
YEAR — Year of Witnessed Fall or Find Recovery
MASS — Recovered mass in kg or g
MINERAL TALLY — Tally of mineralites posted on the Meteorite's 'Mineral List' e.g., N = n(m) = where (1) n= Total number of mineralogical items and (2) m= Total number of IMA-defined minerals.

Table A: 82 Unequilibrated Ordinary Chondrites (ABC…)

METEORITEREGIONKLASSYEARMASSMINERAL TALLY
Acfer 211AlgeriaH3.9;br;S2;W2Find:19911.009 kgN= 8(2)
Adrar 003AlgeriaL/LL3.10;S2;W2Find:1990287 gN=15(9)
Adzhi-Bogdo (stone)MongoliaLL3-6;S2Fall:1949910 gN=17(12) 
ALH 83010AntarcticaLL3.3;S3;W3Find:1983395.2 gN=10(4)
ALH 88020AntarcticaH3.5;S2;W1Find:198853.71 gN= 5(1)
ALH 88036AntarcticaH3.4;S3;W2Find:198826.39 gN= 5(1)
ALH 88044AntarcticaL3.4;S1;W1Find:198821 gN= 4(0)
ALHA76004AntarcticaLL3.3;S2;W1Find:1976305 gN=15(8)
ALHA77176AntarcticaL3.2;S1;W3Find:197754.4 gN=10(5)
ALHA77278AntarcticaLL3.7;W1Find:1977313 gN=16(8)
ALHA77304AntarcticaLL3.7;S2;W2Find:1977650.4 gN=20(10)
AndreevkaUkraineL3Fall:1969600 gN= 4(0)  
BarrattaAustraliaL3.8;S4;W0Find:1845200 kgN=18(11)
BeyroutLebanonLL3.8Fall:19211.100 kgN= 2(0) 
BholaBangladeshLL3-6Fall:19401.047 kgN=16(7)
BishunpurIndiaLL3.15;S4;W0Fall:18951.039 kgN=33(22)
Bo XianChinaLL3.9Fall:19777.5 kgN=38(31)[1 TL]
BovedyUKL3Fall:19695.46 kgN=18(9) 
BremervördeGermanyH/L3.9Fall:18557.25 kgN=20(9)  
Brownfield (1937)USAH3.7Find:193740.96 kgN=21(12)
BuritizalBrazilLL3.2;br;S3;W1Fall:1967210 gN=10(4)
CarraweenaAustraliaL3.9;S4;W2Find:191431.6 kgN=11(5)
CenicerosMexicoL3.7Fall:1988102.5 gN= 4(1) 
ChainpurIndiaLL3.4Fall:19078.2 kgN=32(19) 
Clovis (no. 1)USAH3.6;S2;W5Find:1961283 kgN=23(14)
DengliTurkmeniaH3.8;brFind:1976244 gN=18(10)
DevgaonIndiaH3.8Fall:200112 kgN= 8(3) 
DhajalaIndiaH3.8;S1;W0Fall:197645 kgN=28(17)
DidimTurkeyH3-5;S2;W0Fall:20073.4 kgN=15(10) 
DimmittUSAH3.7;S3;W5Find:1942200 kgN=23(16)
DubrovnikCroatiaL3-6;pm;S3Fall:19511.900 kgN=17(12)
EET 83213AntarcticaLL3.7Find:1983 2.727 kgN=14(7)
FameninIranH/L3Fall:2015630 gN= 7(3)
FermoItalyH3-5Fall:199610.2 kgN= 9(4) 
FlemingUSAH3.7;black;S3;W4Find:19401.75 kgN= 7(2)
FlorenceUSAH3;brFall:19223.64 kgN= 9(4)
GorlovkaUkraineH3.7Fall:19743.62 kgN=18(8) 
Grady (1937)USAH3.7;brFind:19379.3 kgN=19(11)
GüterslohGermanyH3/4;brFall:18511.000 kgN= 3(0) 
HainautBelgiumH3-6;brFall:19349 kgN= 3(0)
HaH 093LibyaLL3.9;S3;W3Find:1995197 gN= 6(2)
HallingebergSwedenL3.4;S3Fall:19441.456 kgN=12(6)  
HedjazSaudi ArabiaL3.7-6Fall:19106.1 kgN=18(11)
HeyetangChinaL3.4;S2;W1Fall:19982.5 kgN= 8(3) 
InmanUSAL/LL3.4;S2;W2Find:19667.25 kgN=23(16)
JulesburgUSAL3.6;S3;W1.5Find:198357.9 kgN=23(13)
KhoharIndiaL3.6;S4;W2Fall:19109.7 kgN=11(7) 
Korra KorrabesNamibiaH3;br; S1; W2Find:1996140 kgN= 7(2)
KrymkaUkraineLL3.2;S3;W0Fall:194650 kgN=34(27) 
LEW 86018AntarcticaL3.1;S2;W4Find:1986502 gN=17(10)
LEW 86134AntarcticaL3.0;S3;W3Find:198628.9 gN= 9(3)
LuponnasFranceH3-5;brFall:175314 kgN= 5(1)
MafraBrazilL3-4;br;S3Fall:1941600 gN=10(4) 
MagombedzeZimbabweH3-5;br; S3Fall:1990667 gN=11(4) 
ManychRussiaLL3.4Fall:19513.56 kgN=11(7)
Mezö-MadarasRomaniaL3.7Fall:185222.7 kgN=30(22) [1 TL]
MoorabieAustraliaL3.8-an;S4-5Find:196514.04 kgN=26(15)
NgawiIndonesiaLL3.6;S3;W2Fall:18831.393 kgN=20(12)
Nio JapanH3-4Fall:1897467 gN=13(4)
NWA 869NW AfricaL3-6;S3;W1Find:2000 2000 kgN=22(14)
NWA 10214MoroccoLL3;S2; W3Find: 20151.816 kgN=14(10)
Oum DreygaWestern SaharaH3-5Fall:200317 kgN= 2(0) 
PalmyraUSAL3Fall:1926135 gN= 2(0)
ParnalleeIndiaLL3.6;S3;W0Fall:185777.6 kgN=30(18) 
PiancaldoliItalyLL3.4Fall:196813.1 gN=25(17) 
Prairie Dog CreekUSAH3.7;S2Find:18932.9 kgN=17(10)
RichfieldUSALL3.7;S4;W1Find:1983 40.8 kgN= 8(3)
Sahara 02500SaharaL3;S4;W1Fall:2001410.9 gN=18(9)
St. Mary's CountyUSALL3.3Fall:191924.3 gN=16(10) 
SemarkonaIndiaLL3.00Fall:1940691 gN=40(30) 
SharpsUSAH3.4Fall:19211.265 kgN=27(20) 
Study ButteUSAH3-6Find:1983417 gN=20(14)
Suwahib (Buwah)Saudi ArabiaH3.8-an;S5;W2Find:1931241 gN=12(5)
TieschitzCzech RepublicH/L3.6;S2;W0Fall:187828 kgN=36(27)
TrenzanoItalyH3/4Fall:185611.8 kgN=12(4) 
Tulia (a)USAH3-4;brFind:191786 kgN= 9(6)
WSG 95300AntarcticaH3.3;S2;W1Find:19952.733 kgN= 7(2)
UdaipurIndiaH3Fall:19762 kgN= 2(0)
VicênciaBrazilLL3.2;S1Fall:20131.540 kgN=13(8)
XinglongquanChinaL3Fall:2008No DataN= 3(0)
ZagWestern SaharaH3-6Fall:1998175 kgN=14(8)
Žd'ár nad SázavouCzech RepublicL3;S2; W0Fall:201445 gN=10(5)

OFFICIAL ABREVIATIONS:
S0—S6: Shock level range, from S0 (unshocked) to S6 (extreme shock)
W0—W5: Weathering level range, from W0 (unweathered) to W5 (extreme weathering)
Shock and weathering levels are mostly from the Catalogue of Meteorites (5/e). In recent years weathering and shock levels have also been provided in the more detailed Meteoritical Bulletin discovery announcements.
TL — Typus Locus or Type Location, the original site of the mineral's discovery.
n TL = Number of new minerals first discovered in the meteorite. The discovered minerals are immediately available via the link to the meteorite's Mindat location site.
Place Names:
ALH, ALHA — Allan Hills, Antarctica; EET — Elephant Moraine, Antarctica; NWA — Northwest Africa; LEW — Lewis Cliff, Antarctica; WSG — Mount Wisting, Antarctica

Our Particular Ensemble: Additional Comments, including some uneven Quasi-'Statistical' Correlations
We merely outline the questions of interest. We shall be interested in general attributes of UOC mineralogical inventories and any specific characteristics of UOC mineralogy which is limned by the fall, find distinction, H/L/LL group distinction; petrologic type.

The individual meteorites selected here are not a random sample and our interest here is not in flushing out the idiosyncrasies of these particular meteorites, per se. We are, however, quite interested in the mineralogical idiosyncrasies of UOCs — and that means we will necessarily need to be mindful that our mineralogical problematics are intertwined with the particular meteorites at hand. All of which is to say that our remarks in Section II will not be as extensive as our investigations in Section III and, especially, in Section IV. Still, there are some important issues about our particular ensemble of meteorites embedded in Table A which we must address immediately.

The most obvious feature of Table A is that our table exhibits an enormous range in the number of cited minerals and mineralites for the various meteorites. Our most mineraliferous meteorite is Semarkona, a very primitive LL3.00 chondrite which fell in 1940. Semarkona is not at all particularly large (only 691 g), but a total of 40 mineralites, including 30 IMA minerals, have been reported in the literature utilized at Mindat. Semarkona may be called an 'ordinary chondrite' but its extraordinary trove of mineralogical ingredients are suggestive of such renown and mineraliferous meteorites as Almahata Sitta [253193](ureilite), Allende (CV3.2), Canyon Diablo (IAB iron), Kaidun (CR2), Murchison (CM2), and Shergotty (martian meteorite). Semarkona is not alone — the 'Mineral Lists' for seven other UOCs report 30 or more mineralites. On the other hand, only two or three mineralite are reported for seven UOCs — all of them falls. These meteorites — if they have been properly classified (presumed here) — contain both olivine and pyroxene, as it were, by definition. Indeed, if we look at our 14 least mineraliferous UOCs (mineralites ≥6) we find that reported masses for half of them are less than a kilogram. The presence of these poorly described meteorites on this list is due primarily to two factors: Our meteorite list (1) contains all witnessed UOC falls and (2) it contains all UOCs highlighted in the Atlas of Meteorites (2015). A more statistically robust ensemble will have to wait for another day — or for uploads from those readers or researchers with access to additional mineralogical information.

However, in spite of the uneven nature of our UOC ensemble, a slightly more careful inspection of our list reveals some intriguing issues. While as might be expected, there is a clear tendency for the more massive meteorites to be cited as hosts for more mineralites (the more material, the more possibilities), there are also some clear exceptions from those tendencies. Semarkona, our most mineraliferous UOC, is the least massive of the 11 most mineraliferous meteorites (mineralites >25). And, Piancaldoli, the least massive of our entire 82 UOC ensemble, is our 12th most mineraliferous meteorite. On the other hand, Oum Dreyga — a recent 17 kg H3-5 fall — is one of only 4 UOCs with merely 2 cited mineralites. Without making premature quantitative judgments, it seems that (1) intrinsic mineralite variability, (2) observer skill and instrumentation, (3) meteorite availability, and (4) complications due to weathering will help determine the completeness and scientific usefulness of each individual meteorite's mineral inventory.

Still, having said all this, the author would like to suggest that the most important feature of Table A alone is that 6 of the 7 most mineraliferous unequilibrated ordinary chondrites reported here are members of the LL-group of ordinary chondrites. Anticipating somewhat the information to be gleaned from coming sections III and IV, we will also find that the LL-group of UOCs (LL3's) are more likely to host exotic inclusions with rare mineralites than are the more numerous H3 and L3 UOC groups. Indeed, the clear scientific implication of the entire set of meteoritic mineralogical records reported here — coupled at times with isotopic and chronometric studies in the more general meteoritic literature — is that the unequilibrated ordinary chondrites have retained records of ancient nebular regions and planetismal homeworlds which are considerably more diverse than those of the equilibrated ordinary chondrites.

With these considerations in mind, we move on to Sections III and IV, our overview of the cited minerals, mineral groups, and other mineralogically significant phases and assemblages found in UOCs. The reader is reminded that as the more detailed Section IV recapitulates important components of Section III, so that he or she may wish to skip ahead to Section IV.

Section III — 94 Mineralites in Unequilibrated Ordinary Chondrites: Overview and Terminology

First take: 94 Mineralites in Unequilibrated Ordinary Chondrites
Salient Features (beginning w. Table B)


Untangling the Various Overlapping Mineralite Categories (IMA minerals, Mineral Groups, Mineral Groups, Solid Solution Series, Varieties, Glasses, Biminerals, Chemically Defined Phases.

As stated earlier, the minerals and mineralites found in the unequilibrated ordinary chondrites or UOCs are quite diverse. Below we discuss briefly what we might expect to observe in most moderately large ordinary chondrites and, specifically, in most moderately large UOCs. In this Section and the next we provide provide two tables (Table B and Table C, respectively) which display important information about reported mineralites. The meteoritical literature regularly employs a formal 'cosmochemical' language (more accurately as a planetochemical language with explicit cosmochemical and implicit mineralogical assumptions). On the other hand, most formal scientific lithological mineralogical discourse is constrained by conventions adapted by the International Mineralogical Association (IMA). One can view the IMA's role as somewhat analogous to the French Academy's role in trying to govern French literary conventions and pretensions. In both instances, the author believes that important institutional decisions about proper discourse are often accompanied by unstated corollaries of questionable generality. These issues will be discussed as they arise, but we must first consider the format of the mineralites — the 94 mineralogically significant items first alphabetically listed in our Table B and then rearranged and relisted for a deeper look in our Table C. We begin our discussion by first addressing the interlinked issues of transparency, uniqueness, and relevance as reflected in the format for Table B. Mindat makes a fundamental distinction between between unique, non-overlapping IMA-defined 'minerals' and all other mineralogical 'items' — items whose application may overlap with other 'items' and may also overlap the defined-minerals. So, as we proceed, the author will take steps to reduce some ambiguities that can be created by the use of these overlapping labels. As we proceed further, we begin to explicitly address a more fundamental scientific issue — the unknown original extraterrestrial provenance of almost all meteorites including, in particular, the ordinary chondrites and their 3 primary planetochemical-cosmochemical ('geochemical') groups, the H, L, and LL chondrites.

As a general rule, when we have a terrestrial rock or mineralogical aggregate in front of us we can usually obtain additional similar samples as needed. Of course, there are exceptions — we don't have any additional 'Hope Diamonds' or 'Ramses II amulets" to study at our leisure. Still, those are exceptions. With meteorites, we are considering a radically different set of constraints. Meteorites are rarer than either diamonds or gold so that as a general rule we almost always have a limited or severely limited amount of material to study with few, if any, options for destructive analysis. And, even more fundamentally important, in the first instance we do not know whence they came and/or where they were formed. For ordinary chondrites — our object of interest — we do believe that all or most of them are fragments of small asteroids that have mostly inhabited the inner solar system [interior to Jupiter's orbit] for the past 4-4.5 billion years. To place our ignorance within a broader intellectual context, we note that almost at a glance most humans can partially determine at least one or two components of any human stranger's continental ancestry. Our knowledge of the original homeworld(s) of all ordinary chondritic meteorites in our possession is much more limited in scope than the limited and frequently biased 'common wisdom' we possess about other members of the human family. It is true that (1) we do have an enormous amount of significant information about ordinary chondritic meteorites and (2) we do have definite information about the original parent bodies of the very small percentage of meteorites that are fragments of the moon, Mars, and (almost certainly) the asteroid 4 Vesta. Still, the drive to diminish the level of ignorance about the original home world or nebular region of formation for any given meteorite is a foundational component of all contemporary meteoritic inquiry. At the present time we continue to move forward in our attempts to discover the Original Parent Bodies (OPBs) of meteorites and their mineralites. Along the way we have learned that the meteorite's chemistry contains information as valuable and relevant as any nugget or jewel in our inquiry. Thus our planetochemical assumptions will guide us as we parlay the mineralogical items displayed at Mindat 'meteorite' location sites into terminology that serves directly the fundamental inquiries of meteoritic research. (More technical mineralogical information will come into play in Section IV.)

The primary categories used by Mindat are (1) IMA-defined minerals and other IMA-referenced mineralogical categories (mineral groups, mineral series, mineral varieties) plus an assortment of additional 'mineralogical items' of practical consequence for various Mindat users. In the Mindat framework the most fundamental distinction is between IMA defined minerals ('valid minerals') and all other listed phases ([mineralogical] 'items'). The author labels this entire assortment of minerals and mineralogical items — plus a number of additional mineralogically significant phases or assemblages frequently encountered in the meteoritical literature —as 'mineralites'. Most of these mineralogical labels are used in precisely the same manner within the meteoritical community. Indeed, in certain formal settings some meteoriticists are at pains to conform with IMA standards in all their published work. Here, however, I note simply that one encounters some elaborately circuitous language to convey fundamental chemical information about meteoritic petrography and mineralogy without breaking IMA labeling categories. Consequently, in this inquiry — wherever feasible — I will try to ground my language in what I believe to be planetological realities. This grounding will require some explicit commentary for a small number of mineralites discussed within this essay.

We will use the rubric of four generic and partially overlapping Categories of Mineralites — Minerals, Standard Mineral Groupings, Mineral Varieties, and Mineralogical Assortae — as suggestive labels or mineralogical 'registers' for the 94 mineralite labels. After brief introductory comments about these 'Generic Categories' , we present Table B. Immediately following Table B we then provide additional commentary on the most important planetological considerations embedded in the records of the various mineralites. Additional more technical classificatory labeling issues are presented in Section IV and in the Appendix.

I. Minerals [e.g., Chromite, Forsterite, Kamacite, Troilite] (N=71).

As defined here a 'Mineral' is a physical aggregate or phase with (1) a definite crystal structure and (2) a defined chemical composition. As expected almost all of the minerals listed here are also IMA-defined minerals (N=69). In 66 instances usage here is identical to normal usage within the scientific community at large. Standard Mindat links provided additional information at the click of a button for these 66 minerals. For the five unlinked 'minerals' usage within meteoritical literature varies from more standard IMA usage to such an extent that we provide clarifications immediately following Table B. In particular, in contrast to IMA usage, we note that — consistent with their relative terrestrial, planetary, and cosmic abundances — extremely rare 'native' terretrial iron is most logically labelled within a planetochemical perspective as a 'variety' of kamacite.

II. Mineral Groupings [e.g., Clinopyroxene, Feldspar, Limonite, Olivine] (N=14).

In many instances it is essential to refer to various groupings of minerals without specifying the specific mineral involved. At some levels this seems to be a trivially obvious matter which would require no further comment. Minor complications frequently arise. Clinopyroxene and Orthopyroxene are readily seen as 'Mineralogical Subgroups', distinguished by their mineralogy. However, K-Feldspar is also listed here as a Mineralogical Subgroup, but it is a chemically defined subgroup. Furthermore, there are two additional realities which can complicate matters in a hurry. In the first instance a specific mineral can be encompassed by more than one grouping label [e.g., diopside is both a 'clinopyroxene' and a 'pyroxene'] so that not only are multiple mineralogical phases assigned [lumped together] into a single category, but an individual phase may be assigned to different mineralogical categories. Indeed, within the meteoritical literature the use of these overlapping groupings occurs quite frequently when underlying planetological or cosmochemical characteristics are fundamental to the topic at hand. Our discussion of the chemically defined 'Fe-Ni metal' mineralite(s) and the plagioclase feldspars will introduce some naming protocols designed to preserve mineralogical precision and planetochemical transparency. We also note that generic terms such as 'limonite' and 'caliche' can serve as important cautionary markers for interpreting possible preterrestrial, but weather-vulnerable phases.

III. Mineral Varieties [e.g., Chromspinel, Cliftonite, Fassaite] (N=6).

Naturally it is often important to refer to variations within individual minerals ('varieties') as both chemical and petrographic features can provide critical information about the history of a mineral and its encompassing rock. The four chemically defined varieties below are often important in tracing the thermal and planetochemical history of meteorites. Indeed, 'Fassaite' is, perhaps, the most surprisingly important of all 6 varieties reported here. This Al-, Ti-rich augite appears to be derived from a high-temperature region which is poorly represented among equilibrated ordinary chondrites. [It may be that the presence of fassaite in the unequilibrated ordinary chondrites may not be unrelated to its prominence among the angrite achondrites. The angrites are a very small but very enigmatic meteoritic group whose relationship to the present-day asteroid belt is currently quite opaque.] We further note that Martensite, defined by Mindat as a disordered variety of kamacite, might be more aptly described as a 'metallic glass'. Examined in detail, Martensite appears to represent both (1) metastable varieties of super-cooled Fe-Ni metal which is sometimes too Ni-rich to transform into pure kamacite and (2) shock-melted melted kamacite which subsequently cooled too quickly to revert to kamacite.

IV. Mineral Assortae including occasional Chemically-defined Mineralites [e.g., Ca-poor Fe-Ni metal, Glass, Pyroxene, Silica, Tungsten…] (N=3).

In Tables B and C we explicitly utilize 3 terms which do not fall into the Minerals, Mineral Groups, or Mineral Varieties rubric. These 3 terms are Glass, Maskelynite, and (bi-mineralic) Plessite. Largely unmentioned explicitly in the Tables are IMA 'outdated' terms that have also been employed in constructing the Tables. But we single out chemically-defined mineralites for special attention. The utilization of chemical information in the definition of a mineralite is as much a social construct as the immediate consequence of a physical measurement. We note that within the meteoritical community planetochemical (a.k.a., 'geochemical') information is utilized in classifying meteorites. In this instance, the very act of labeling a meteorite a member of the ordinary chondrite class implies that someone has determined that any crudely representative specimen of the meteorite is comprised mostly of moderately Mg-rich olivine and pyroxene(s). Other common terms of meteoritical literature (e.g., Ca-poor Clinopyroxene, Ca-rich pyroxene, Ca-rich phosphate) have been folded into our own linguistic emphases and definitions. Furthermore, the additional determination that an ordinary chondrite belongs to a specific petrologic type has mineralogical implications. For example, unless it has experienced extreme shock, the predominant pyroxene of a properly classified H6, L6, or LL6 meteorite should be almost entirely orthopyroxene.

Table B: 94 Minerals and Mineralites in 82 UOCS


Our 94 mineralites are alphabetically arranged here for ease of reference. The categories themselves are somewhat abbreviated because of space limitations. Indeed, the categories are, at times, merely suggestive.

MINERALITE = The mineralite's name, the name or label for the mineral or mineralogically significant item.
REGISTER = Mineral Register, the 'type' of mineralogical label. The mineral register contains an implicit expectation about the overall range of the mineralite's label.
Caveat: Usage of the 5 Mineralite terms without Mindat Links (black print) — as used in this essay — are defined in the Appendix.
HOST# = The number of individual meteorite hosts cited for the mineralite.
CHEMISTRY = A planetological chemical descriptor of the mineralite and its chemical and mineralogical venue. For many applications, the term 'geochemistry' would be applicable. However, in scientific discussions of meteorites a planetochemical venue is alway primary and — with a few rare exceptions — ultimately dispositive.
PROVENANCE = Statistical Mineralogical Expectations and/or Formational Venue; A very flexible verbal proxy for embedded expectations which might eventually guide us to the original formational setting of the mineralite or the meteorite.
FALL# = The number of witnessed meteorite falls which are cited here as mineralite hosts, e.g., the mineralite appears on the 'Mineral List' at the meteorite's Mindat 'location site'.
FIND# = The number of recovered meteorite finds whose Mindat 'location sites' report the present of the mineralite.
HOST METEORITES = For mineralites that are reported here for only 1 or 2 ordinary chondrite hosts we identify the host(s). Otherwise we provide very little additional information.

Table B: 94 Minerals and Mineralites in 82 UOCs

MINERALITEREGISTERHOST#CHEMISTRYPROVENANCEFALL#FIND#HOST METEORITE(S)
AenigmatiteIMA Mineral1TektosilicaterareFall(1) Adzhi-Bogdo (stone)
AlbiteIMA Mineral9TektosilicateOccasional accessoryFalls(7)finds(2)Multiple Hosts
AnorthiteIMA Mineral11TektosilicateHi TFalls(7)finds(4)
AntitaeniteMineral1Fe-Ni metalrareFall(1) Vicência (LL3.2)
'Apatite'Series22PhosphateExpectedFalls(16)finds(6)Multiple Hosts
AragoniteIMA Mineral1CarbonateEarth&Skyfind(1)Dimmitt (H3.7)
AugiteIMA Mineral27InosilicateanticipatedFalls(18)finds(9)Multiple Hosts
AwaruiteIMA Mineral2Fe-Ni metalrareFalls(2) Semarkona & Krymka
'Biotite'Series1PhyllosilicateHydrationFall(1)Bo Xian (LL3.9)
CalciteIMA Mineral2CarbonaterareFalls(2) Semarkona & Bo Xian
ChlorapatiteIMA Mineral14 PhosphateExpectedFalls(8)finds(6)Multiple Hosts
ChromiteIMA Mineral50Oxide (spinel)UbiquitousFalls(28)finds(22)Multiple Hosts
'Chromspinel'Spinel variety11Oxide (spinel)occasionalFalls(3)finds(8)
CinnabarIMA Mineral2SulfideChalcophileFalls(2)Didim; Tieschitz
'Cliftonite'Graphite variety1ElementPseudomorphfind(1)Grady (1937) (H3.7)
ClinoenstatiteIMA Mineral13 Inosilicatelow O-fugacityFalls(7)finds(6)Multiple Hosts
'Clinopyroxene'Min · Subgroup41 InosilicateUOCsFalls(22)finds(19)Multiple Hosts
CoheniteIMA Mineral5Carbidelow O-fugacityFalls(3)finds(2)
CopperIMA Mineral17ElementAnticipatedFalls(13)finds(4)Multiple Hosts
CorundumIMA Mineral6OxideHigh T; StardustFalls(6)
CristobaliteIMA Mineral5 InosilicateLateFalls(4)find(1)
CoveliteIMA Mineral1SulfiderareFall(1) Tieschitz (H/L3.6)
DaubréeliteIMA Mineral1 SulfiderareFall(1) Semarkona (LL3.00)
DiamondIMA Mineral11ElementrareFalls(6)finds(5)Stardust
DiopsideIMA Mineral21InosilicateExpectedFalls(12)finds(9)Multiple Hosts
DolomiteIMA Mineral1CarbonateEarth&SkyFall(1) Bo Xian (LL3.9)
EnstatiteIMA Mineral13Inosilicatelow O-fugacityFalls(9)finds(4)Multiple Hosts
'Fassaite'Augite Variety10 InosilicateHi TFalls(6)finds(4)Multiple Hosts
FayaliteIMA Mineral8NesosilicateLateFalls(8) Late aggregates
'Feldspar'Mineral Group55 Tektosilicatelow O-fugacityFalls(32)finds(23)Almost all UOCs
Fe-Ni metalChemical Set77Primordial MetalExpected!Falls(42)finds(35)Almost all UOCs
'Ferroaugite'Augite variety1InosilicaterareFall(1) Chainpur (LL3.4)
FerrosiliteIMA Mineral1Inosilicaterarefind(1)ALHA76004 (LL3.3)
FluorapatiteIMA Mineral1 PhosphaterareFalls(1) Krymka (LL3.2)
ForsteriteIMA Mineral37NesosilicateLow O-fugacityFalls(15)finds(22)Multiple Hosts
'Gehlenite'Mineral Group2SorosilicaterareFalls(2) Sharps & Semarkona
'Glass'Glass52Disordered SilicateShockFalls(29)finds(23)Ubiquitous
GoethiteIMA Mineral1Hydrous oxideWeatherate find (1)Brownfield (1937) (H3.7)
GraphiteIMA Mineral17ElementLow O-fugacityFalls(11)finds(6)Multiple Hosts
HaliteIMA Mineral1ChloriderareFall(1)Zag
HaxoniteIMA Mineral2CarbideLow O-fugacityFall(2) Semarkona & Ngawi
HematiteIMA Mineral1OxideWeatheratefind(1)Inman
HercyniteIMA Mineral1Oxide (spinel)rareFall(1) Dhajala (H3.8)
HiboniteIMA Mineral10OxideHi TFalls(7)finds(3)Inclusions
IlmeniteIMA Mineral24OxideCommon accessoryFalls(13)finds(11)Multiple Hosts
IsocubaniteIMA Mineral5SulfideEarth&SkyFall(1)finds(4)
'K Feldspar'Min · Subgroup6TektosilicateLateFalls(6) Inclusions
KamaciteMineral55Fe-Ni metalExpected!Falls(32)finds(23)Almost all UOCs
KosmochlorIMA Mineral1Inosilicaterarefind(1)Inman (L/LL3.4)
'Limonite'Generic Group24Hydrous oxides WeatherateFalls(2)finds(22)Common in Finds
MaghemiteIMA Mineral2Hydrous oxideEarth&SkyFalls(2)Semarkona & Bishunpur
MagnesioferriteIMA Mineral1Oxide (spinel)rareFall(1) Bo Xian (LL3.9)
MagnetiteIMA Mineral20Oxide (spinel)Earth&SkyFalls(11)finds(9)Multiple Hosts
MarićiteIMA Mineral1CosmochemistryrareFall(1) Bishunpur (LL3.15)
'Martensite'Kamacite Var · 2Fe-Ni metalShock&coolFall(1)find(1)Zag & Barratta
'Maskelynite'Glass6SilicateShockFalls(2)finds(4)
MeliliteIMA Mineral4SorosilicateSi-poor settingFalls(2)finds(2)
MercuryIMA Mineral2ElementChalcophileFalls(2)Didim; Tieschitz
MerrihueiteIMA Mineral1 CyclosilicateInclusionFall(1)Mezö-Madaras (L3.7)
MerrilliteIMA Mineral25PhosphateExpectedFalls(16)finds(9)Multiple Hosts
'Meteoritic Iron'Generic Set26Fe-Ni metalExpectedFalls(13)finds(13)Multiple Hosts
MoissaniteIMA Mineral3CarbiderareFalls(2)find(1)stardust
'Nepheline'IMA Mineral11TektosilicateAccessoryFalls(8)finds(3)
NickelphosphideIMA Mineral1Phosphiderarefind(1)Inman (L/LL3.4)
NieriteIMA Mineral3NitrideUtter ReductionFalls(1)finds(2)Stardust
'Olivine'Series82NesosilicateExpected!Falls(47)finds(35)In all UOCs
OrthoclaseIMA Mineral3TektosilicateLateFalls(3) Inclusions
'Orthopyroxene'Min · Subgroup45InosilicateAnticipatedFalls(26)finds(19)Multiple Hosts
OsumiliteIMA Mineral1CyclosilicaterareFall(1) Bishunpur (LL3.15)
PanethiteIMA Mineral1PhosphaterareFall(1) Bishunpur (LL3.15)
PentlanditeIMA Mineral9SulfideEarth&SkyFalls(5)finds(4)
PerovskiteIMA Mineral6OxideHigh TFalls(4)finds(2)
PigeoniteIMA Mineral17InosilicateQuik CoolFalls(11)finds(6)Multiple Hosts
'Plagioclase'Series49TektosilicateExpectedFalls(29)finds(20)Multiple Hosts
'Plessite'Bimineral8Fe-Ni metalQuick coolFalls(5)finds(3)
PyrrhotiteIMA Mineral5SulfideEarth&SkyFalls(5)
QuartzIMA Mineral2TektosilicateLateFalls(2) Adzhi-Bogdo*; Bo Xian
RoedderiteIMA Mineral3CyclosilicaterareFalls(2)find(1)
RutileIMA Mineral4OxideMinor accessoryFalls(2)finds(2)
'Scapolite'Series5TektosilicaterareFalls(3)find(2)Late
SchreibersiteIMA Mineral8PhosphideOccasionalFalls(7)find(1)Multiple Hosts
SilverIMA Mineral1ElementrareFall(1) Krymka (LL3.2)
'Smectite'Mineral Group4PhyllosilicateHydrationFalls(4)
SodaliteIMA Mineral8TektosilicateHydrationFalls(4)finds(4)
SpinelIMA Mineral31Oxide (spinel)Occasional AccessoryFalls(17)finds(14)Multiple Hosts
TaeniteIMA Mineral46Fe-Ni metalAnticipatedFalls(30)finds(16)Multiple Hosts
TetrataeniteIMA Mineral16Fe-Ni metalAnticipatedFalls(11)finds(5)Multiple Hosts
TridymiteIMA Mineral8TektosilicateLateFalls(4)finds(4)
TroiliteIMA Mineral73SulfideUbiquitousFalls(39)finds(34) In almost all UOCs
TungstenIMA Mineral1ElementrareFall(1) Krymka (LL3.2)
WadsleyiteIMA Mineral1NesosilicateShock!Fall(1)Bo Xian (LL3.9)
WüstiteIMA Mineral2oxideIn crustsFalls(2)Piancaldoli & Bo Xian
ZhanghengiteIMA Mineral1Metal AlloyrareFall(1)Bo Xian (LL3.9)
ZirconIMA Mineral2NesosilicateHigh T Fall(1)find(1)NWA869; Adzhi-Bogdo*

Abbreviation: Adzhi-Bogdo* = Adzhi-Bogdo (stone)
Terminology:
K-Feldspar = Mindat 'K Feldspar'
Plagioclase is an exact synonym for Mindat 'Albite-Anorthite Series', itself an abbreviation for the 'Albite-Anorthite Solid Solution Series ·
Whitlockite in meteorites is normally read as 'Merrillite · '

Redundancies:
Two important terms which are either redundant or mineralogically ambiguous are not explicitly tallied here ·
Pyroxene — Classification as an ordinary chondrite implies that either Ca-poor orthopyroxene or Ca-poor clinopyroxene is present ·
Silica — Cristobalite, Quartz, and Tridymite are the 3 most likely silica polymorphs in UOCs ·

Protocols for Clarifying the Planetological and Planetochemical Significance of Observed Mineralites: Planetochemically defined categories, Restricted use of broadly defined terms (esp · 'End Member' terms), Preferred meteoritical categories… ·

The most straightforward protocol to reduce chemical ambiguities in the description of meteoritic minerals is to restrict the use of IMA allowable terms in a way that prevents or at least lessens those ambiguities · Within the past two decades there has been a systematic tendencies within the IMA to redefine various solid-state solution series as a 'simple' combination of the two (or more) most important components with an actual mineral aggregate being defined as an 'instance' of the predominant component · Thus, for example, one sees all most all 'orthopyroxene' (essentially a solid solution series of Mg-rich enstatite and Fe-rich ferrosilite in many instance) as either the mineral 'Enstatite' [if En ≥ 50 mol%] or 'Ferrosilite' [if Fs ≥ 50 mol%] · Such redefinitions may have positive consequences for terrestrially-minded geochemists, geologists, and mineralogists of the IMA · However, several of them wreak havoc with the meteoritic classification system —a system designed to help determine the original solar system body or bodies of origin for all meteorites · To partially restore scientific relevance to meteoritic mineralogical terminology, this author usually restricts the use of the end member terminology to a more relevant proper subset of the IMA-defined mineral · In this instance the author restricts his use of the term 'Enstatite' to orthopyroxenes with En ≥ 90 mol% · Orthopyroxenes with compositions En 90-50 mol% are simply labelled Orthopyroxene · Or, as the author would have it, Enstatite with En ≥ 90 mol% is Enstatite sensu stricto · The author has used this protocol in (1) preparing this essay and its Tables and (2) in uploading a substantial portion of the mineralites which appear on Mindat Mineral Lists for these meteorites · Needless, to say, this particular approach is only one approach to a difficult issue · It is, however, closer to the formal language of scientific meteoritical discourse and even closer to most informal meteoritical discourse · We highlight here only the most important nuances of Table B · We note also that our protocol is always preceded by a 'whenever possible' as practical difficulties often intervene · [The author, for example, cannot consult [read] an original text in Chinese or Polish when terminology in an English abstract is ambiguous · ]

Set A · 11 Minerals, Mineral Groups, Mineral Subgroups
Minerals and Mineralites that are used in Table B with a restricted range in order to (1) reduce ambiguities between overlapping mineralite categories and/or (2) to minimize conflicts between planetological inquiries and terrestrially derived geochemical categories · [Our most obvious concern is to insure that extremely Mg-rich, Fe-poor silicates (esp · olivine and pyroxenes) are recognized as such · ]

1. Albite — Plagioclase of chemical compositionAb ≥90 mol% ·
2. Anorthite — Plagioclase of chemical composition An ≥90 mol% ·
3. Clinoenstatite — Clinopyroxene of chemical composition En ≥90 mol% [unusually Mg-rich pyroxene] ·
4. Clinopyroxene — Mg-rich, Ca-poor varieties of Clinopyroxene with En 50-90 mol% ·
5. Enstatite — Orthopyroxene of composition En ≥90 mol% [unusually Mg-rich pyroxene] ·
6a · Feldspar — (A) Feldspar with a significant orthoclase component (Or>5) ·
6b · Feldspar — (B) Feldspar with an unknown orthoclase component ·
7. Forsterite — Olivine of composition (Fo ≥90 mol%) [unusually Mg-rich olivine] ·
8. Limonite — Generic term for reports of hydrous iron oxide weatherates when specific phases such as Goethite are not reported ·
9. Olivine — Olivine with of composition Fo 50-90 mol% [non-'End Member' olivine] ·
10. Orthopyroxene —Orthopyroxene with composition En 50-90 mol% [Non-'End Member' orthopyroxene] ·
11. Plagioclase — Plagioclase of chemical composition Ab <90 mol% and An <90 mol% [Non-'End Member' plagioclase] ·

Set B · 2 New and/or non-IMA Minerals and Mineralites ·
1. Fe-Ni Metal — Preferred term in the meteoritical literature for meteoritic iron-invariably-accompanied-by-nickel and other accompanying siderophiles characteristic of extraterrestrial origins ·
2. Kamacite — The predominant mineral within the Fe-Ni grains and aggregates of ordinary chondrites ·

Set C · 3 Mineralogically significant chemically defined and mineralogically defined terms · Terms which are present on Mindat Mineral lists for individual meteorites, but which are not tallied here ·

1. Meteoritic Iron — Fe-Ni metal which has not been mineralogically characterized ·
2. Pyroxene — Present, by definition, in all UOCs · Used here primarily when the pyroxenes within a meteorites are incompletely described ·
3. Silica — Common silica polymorphs reported here include cristobalite, quartz, and tridymite · The reports of mineralogically undescribed silica ·

___Implications: UOCs Mineralites — A first peek behind the numbers of Table B ·


Over forty years ago as our current classification system gradually emerged, Brian Mason noted on various occasions that the primary constituents of ordinary chondrites are olivine, Ca-poor pyroxene, plagioclase, troilite, Fe-Ni metal (both kamacite and taenite) accompanied by minor diopsidic clinopyroxene as well as accessory chromite and Ca-phosphate · Following his summaries of the 1960's and 1970's one might have even concluded that these constituents would be present in almost every moderately large ordinary chondrite which had not been overly altered by severe shock or weathering · Looking at the results here, one might also argue that this is probably true for the UOCs as well · Our results do not in themselves confirm that these constituents are in fact present in the overwhelming majority of UOCs, but one could easily argue that the combination of classificatory reports of varying quality and the inherent difficulties of working with small and sometimes very weathered meteorites would be expected to create a very uneven result similar to our present results · Before we tackle that issue, let us instead review the results that we have · The first step in classifying an ordinary chondrite is invariably the determination of its olivine and, usually, its Ca-poor pyroxene composition · While the abstracts and announcements do not always reference the olivine and pyroxene compositions explicitly, we have assumed here that the classifications have been properly performed and that olivine and Ca-poor pyroxene are, in fact, present in all our ordinary chondrites · For the other expected phases or mineral sets we have the following results · Fe-Ni metal has been reported in 77 UOCs, troilite in 73 UOCs, the feldspar in 54 UOCs, the chromite in 50 UOCs, Ca-rich clinopyroxenes in 33 UOCs, and Ca-rich apatite and/or merrillite in 33 UOCs · Our task will be to consider the results for these minerals or mineralite sets in turn · One question we consider is whether our mineralogical inventories are understandably incomplete or whether there are addressable issues which could be used to improve the quality and scientific relevance of our obviously incomplete inventories · One more thing: we will also find some features of UOC mineralogy just under the statistical problematics that are quite intriguing ·

We note first that we expect to find (unoxidized) Fe-Ni metal in almost every UOCs · Of course, we might not find Fe-Ni metal in very weathered finds · And, it is actually unclear how much Fe-Ni metal would be expected in the most pre-terrestrially oxidized members of the LL-group meteorites · In our ensemble Fe-Ni has not been reported for five meteorites on our list, but these meteorites are not finds · Instead all of them are falls and only one of them (Beyrout) is an LL3 chondrite · These meteorites are best simply described as very incompletely described meteorites — only olivine and pyroxene have been reported for 4 of them and only 4 phases were reported for Andreevka phases · A more important problem is that kamacite is reported only for 55 meteorites · Experienced observers such as Rubin and Ramdohr observe kamacite in over 99% of the OC they have observed and in the great majority of UOCs · Fe-Ni metal in UOCs is frequently dispersed into small and sometimes spherical grains · However, attention to euhedral and/or subhedral crystal forms and to colors (tints) utilizing oil immersion would presumably allow for a much higher recognition percentage for kamacite than reported here · Similar considerations apply for troilite · Even experienced observers may merely mention the presence of 'sulfides' in a studied meteorite ·

Recognition of expected plagioclase presents several difficult problems · Normative calculations based on chemical analysis suggests that — as is true of equilibrated ordinary chondrites (EOC) — plagioclase of bytownite composition should be the dominant form of plagioclase in most UOCs · Plagioclase is, in fact, reported directly in 43 instances, but it is not always accompanied by a chemical readout · If we include the endmember constituents anorthite and albite we can report plagioclase citations in a total of 48 UOCs · Plagioclase grains in UOCs are usually quite small and of variable and/or uncertain composition · In a few instances, K-rich feldspar is also present · Indeed, feldspar is explicitly reported in 10 instances · However, the label feldspar is ambiguous — in the instances reported here it is clear that the term 'feldspar' may refer either to feldspar with significant K content or to feldspar of uncertain chemical constituents · What we can say based on the records cited here is that feldspar is present in at least 54 members of our ensemble and that in at least 49 instances the feldspar appears to have a significant plagioclase component ·

And, we have waited before adding an additional consideration · Primary glass is almost always present in the UOCs — and explicitly reported for 52 of our group · And this glass is normally dominated by a plagioclase normative component (maskelynite) · The reason is quite simple — UOCs were assemble from glass-rich chondrules rich in quickly cooled silicates and, during the accretion process, experienced additional collisional heating events · And while all of the common UOC silicates have experienced various episodes of vitrification and devitrification, plagioclase is by far the most easily vitrified member of the lot · Indeed, while maskelynite is specifically cited in 6 of our sources, it is quite clear that it has been seriously underreported here · It is common knowledge that plagioclase glass is almost alway an important component of chondritic glass and doing a study of the relative abundances of such glass is not alway a high priority · What does seem important and is perhaps worthy of further attention is the extent to which we can say that all or almost all of the plagioclase in a particular meteorite has been maskelynized · While there are a few instances where this issue has been addressed, this author is left with the distinct impression that these instances are actually very few · As stated above, there may be good reasons why such detailed studies have not been made · But it also leaves standing the contrast between the situation with the well-equilibrated type 5 and 6 ordinary chondrites whose plagioclase is usually quite prominent (or, occasionally, converted almost entirely into readily recognized glass) ·

Ca-rich pyroxenes (diopside and augite) are reported here from 33 UOCs · In 14 instance both phases are reported from the same meteorite · The relatively sparse reporting of mineralogical identification of Ca-rich clinopyroxenes is perhaps the most jarring 'statistic' among the relatively abundant UOCs minerals · While Ca-rich pyroxenes are not essential for classification, they usually constitute a little more than 5% of a normal OC · We expect these phases in UOCs both as residues of early high temperature condensation and, to a lesser extent, as exsolution products of metamorphism · Quite interestingly, augite (and fassaite, an augite variety) appear to be relatively abundant in LL group · Pigeonite, with an intermediate level of Ca-enrichment, apparently born of quick cooling events, is reported from 17 separate meteorites (usually in meteorites that also have augite and/or diopside) · Again, there seems to be an enhancement in reported pigeonite from the LL3 meteorites ·

Reports of chromite for only 50 of our UOCs is also problematic · One would assume, prima facie, that observations for a large fraction of the mineralites reported here were largely based on thin sections with minimal use of either the microprobe and/or oil-immersion techniques · Chromite in has been reliably observed since the 19th century by experienced observers · We also note here that Ramdohr (1973) observed chromite in over 99% of the 200+ ordinary chondrites studied including all 14 UOCs ·

On the other hand, reports of Ca-poor phosphate minerals for only 33 of the UOCs does not seem so problematic, at least to this observer · Phosphate minerals in meteorites are usually small and not easily mineralogically characterized with a petrographic microscope · Even Mason's exemplary reports in the 60's would often end with words to the effect that small grains of either apatite or merrillite were present · Of course, reports of 'Ca-phosphates' and 'either apatite or merrillite' do not contribute to Mindat Mineral Lists — or to the tallies reported here · One positive change in recent years has been the utilization of both apatite and merrillite for absolute dating utilizing Pb-207/Pb-206 isotope measurements · In this instance, the immediate scientific rewards of extra effort and new techniques are beginning to increase our knowledge of several phosphate bearing minerals ·

Also of interest are the 26 mineralites reported here from a single UOC Host · Fourteen of these 'solo' reports involve LL-hosts · Indeed, 5, 3 and 2 phases are reported here only from Bo Xian (LL3.9), Krymka (LL3.2), and Bishunpur (LL3.15), respectively · This over-representation of exotic minerals and phases in the LL3s and of multiple-exotic LL3 hosts is extremely suggestive · While overall the LL chondrites are suspiciously similar to the L chondrites, the LL chondrites themselves appear to contain components of a mineralogical stream which is anomalous relative to both the H and L ordinary chondrite groups ·

We will consider some of the various phases associated with these primary minerals in Section IV ·

Section IV: The 94 Individual Mineralites Individually Considered [Planetochemical Significance]

Full Title Second Take — 94 Mineralites in Unequilibrated Ordinary Chondrites: Planetological Venues, Cohorts and Statistical Notes (w · Table C)
[Brief recapitulations of Section III and extensive descriptions of individual minerals and mineralites · ]

In this section we examine the tallies from the perspective of several loosely defined planetological cohorts under a combined mineralogical and chemical rubric · We will also pay special attention to the frequency that various mineralites appear in the Mineral Lists of our 82 UOCs · We begin with the default assumption that our tallies are seriously incomplete, but we also suspect that our studied set of meteorites is large enough that some conservative working hypotheses can be articulated · Scientific questions raised in earlier sections and discussed here in somewhat more detail include:

(1) Do UOCs sample a larger set of compositional 'streams' than might be expected from studied equilibrated ordinary chondrites (EOCs) of Types 4-6?
(2) To what extent are trends in mineralogical populations shaped by a few mineraliferous meteorites?
(3) Are their identifiable differences in the mineralogical populations of the H-, L-, and LL-ordinary chondrites?
(4) Do such population differences — if present — include oxidation and/or hydration episodes?
(5) Can we deconvolve the effects of weathering in UOCs finds to such an extent that studies of these finds amplify and strengthen the results derived from studies of witnessed falls?

The mineralites of Table C will be arranged into 9 major categories: Cosmic Iron, Other Elements and Metallic Alloys, Carbon and Carbides, Sulfides, Halides/Nitrides/Phosphides, Phosphates, Carbonates, Oxides, and Disordered Silicates (or, Silicates*) · The silicates will be further divided into several subcategories · Weatherates, phases and aggregates normally produced by terrestrial weathering, will constitute a separate category · These categories are somewhat arbitrary as they by necessity differentiate categories that often overlap each other, but these 9 categories and their subcategories will allow us to address some important questions related to the history of ordinary chondritic meteorites ·

Table C: 94 Mineralites in 82 UOCs (Planetochemical Cohorts)


TABLE C CATEGORIES (Same as Table B categories)
MINERALITE — Name of Mineral, Mineral Group, Mineral Variety or Mineralogically Significant Item ·
(MINERAL) REGISTER — Specific type of Mineralite Register
HOST — Number of UOC hosts reported here for the specific mineralite
CHEMISTRY — Generic Planetochemical or Cosmochemical Category of Mineralite.
PROVENANCE — Mineralogical Provenance: Quasi-statistical expectations OR Specifics of Formational Venue [Cf. Table B]
HOST STONES — Individual meteorite hosts for Rare Phases; Host tendencies; DEFAULT : Found in multiple UOC Hosts [left blank[.

94 Mineralites in 82 Unequilibrated Ordinary Chondrites (Planetochemical Cohorts)

MINERALITEREGISTERHOSTCHEMISTRYPROVENANCEFALLFINDHOST STONES
COSMIC IRON
Fe-Ni metalChem Set77Primordial!Expected!Falls(42)finds(35)
KamaciteMineral55Fe-Ni metalExpected!Falls(32)finds(23)
TaeniteIMA Mineral46Fe-Ni metalAnticipatedFalls(30)finds(16)
TetrataeniteIMA Mineral16Fe-Ni metalAnticipatedFalls(11)finds(5)
'Plessite'Bimineral8Fe-Ni metalQuick coolFalls(5)finds(3)
AwaruiteIMA Mineral2Fe-Ni metalRareFalls(2) Semarkona & Krymka
'Martensite'Kamacite Var.2Fe-Ni metalShock&coolFall(1)find(1)Zag & Barratta
'Antitaenite'Mineral1Fe-Ni metalrareFall(1) Vicência (LL3.2)
ELEMENTS; ALLOYS
CopperIMA Mineral17ElementAnticipatedFalls(13)finds(14)
MercuryIMA Mineral2ElementChalcophileFalls(2)Didim; Tieschitz
SilverIMA Mineral1ElementrareFall(1) Krymka (LL3.2)
TungstenIMA Mineral1ElementrareFall(1) Krymka (LL3.2)
ZhanghengiteIMA Mineral1Metal AlloyrareFall(1)Bo Xian (LL3.9)
CARBON;CARBIDES
GraphiteIMA Mineral17ElementLow O-fugacityFalls(m)finds(n)
DiamondIMA Mineral11ElementRareFalls(6)finds(5)
'Cliftonite'Graphite variety1ElementPseudomorphfind(1)Grady (1937) (H3.7)
CoheniteIMA Mineral4Carbidelow O-fugacityFalls(3)finds(2)
MoissaniteIMA Mineral3CarbiderareFall(1) Krymka (LL3.2)
SULFIDES
TroiliteIMA Mineral73SulfideUbiquitousFalls(39)finds(34)Almost all UOCs
PentlanditeIMA Mineral9SulfideEarth&SkyFalls(5)finds(4)
IsocubaniteIMA Mineral5SulfideEarth&SkyFall(1)finds(4)
PyrrhotiteIMA Mineral5SulfideEarth&SkyFalls(5)
CinnabarIMA Mineral2SulfideChalcophileFalls(2) Didim; Tieschitz
CoveliteIMA Mineral1SulfiderareFall(1) Tieschitz (H/L3.6)
DaubréeliteIMA Mineral1 SulfiderareFall(1) Semarkona (LL3.00)
HaxoniteIMA Mineral1CarbideLow O-fugacityFalls(2) Semarkona; Ngawi
NITRIDES; PHOSPHIDES; &&
HaliteIMA Mineral1ChloriderareFall(1)Zag
NieriteIMA Mineral3Nitridelow O-fugacity!;StardustFall(1)finds(2)
SchreibersiteIMA Mineral8PhosphideOccasional accessoryFalls(7)find(1)
NickelphosphideIMA Mineral1Phosphiderare Find(1)Inman (L/LL3.4)
PHOSPHATES
MerrilliteIMA Mineral25PhosphateExpectedFalls(16)finds(9)
'Apatite'Mineral Series22PhosphateExpectedFalls(16)finds(6)
ChlorapatiteIMA Mineral14PhosphateExpectedFalls(8)finds(6)
FluorapatiteIMA Mineral1PhosphaterareFall(1) Krymka (LL3.2)
MarićiteIMA Mineral1PhosphatesrareFall(1) Bishunpur (LL3.15)
PanethiteIMA Mineral1PhosphaterareFall(1) Bishunpur (LL3.15)
CARBONATES
CalciteIMA Mineral2CarbonaterareFalls(2) Semarkona & Bo Xian
AragoniteIMA Mineral1CarbonateEarth&Skyfind(1)Dimmitt (H3.7)
DolomiteIMA Mineral1CarbonateEarth&SkyFall(1) Bo Xian (LL3.9)
OXIDES
ChromiteIMA Mineral50Oxide (spinel)UbiquitousFalls(28)finds(22)
SpinelIMA Mineral31Oxide (spinel)Occasional AccessoryFalls(17)finds(14)
IlmeniteIMA Mineral24OxideCommon accessoryFalls(13)finds(11)
MagnetiteIMA Mineral20Oxide (spinel)Earth&SkyFalls(11)finds(9)
'Chromspinel'Spinel variety10Oxide (spinel)occasionalFall(3)finds(7)
HiboniteIMA Mineral10OxideHi TFalls(7)finds(3)
PerovskiteIMA Mineral6OxideHigh TFalls(4)finds(2)
CorundumIMA Mineral6OxideHigh T; StardustFalls(6)
RutileIMA Mineral4OxideMinor accessoryFalls(2)finds(3)
MagnesioferriteIMA Mineral1Oxide (spinel)rareFall(1) Bo Xian (LL3.9)
HercyniteIMA Mineral1Oxide (spinel)rareFall(1) Dhajala (H3.8)
THE SILICATES
'Olivine'Mineral Series82NesosilicateExpected!Falls(47)finds(32)In all UOCs
ForsteriteIMA Mineral37NesosilicateLow O-fugacityFalls(15)finds(22)
FayaliteIMA Mineral8NesosilicateLateFalls(8)
ZirconIMA Mineral2NesosilicateHigh T Fall(1)find(1)NWA 869; Adzhi-Bogdo*
WadsleyiteIMA Mineral1NesosilicateShock!Fall(1)Bo Xian (LL3.9)
'Orthopyroxene'Min. Subgroup45InosilicateAnticipatedFalls(26)finds(19)
'Clinopyroxene'Min. Subgroup42InosilicateUOCsFalls(23)finds(19)
AugiteIMA Mineral27InosilicateanticipatedFalls(18)finds(9)
DiopsideIMA Mineral21InosilicateExpectedFalls(12)finds(9)
PigeoniteIMA Mineral16InosilicateQuik CoolFalls(10)finds(6)
ClinoenstatiteIMA Mineral13Inosilicatelow O-fugacityFalls(7)finds(6)
EnstatiteIMA Mineral13Inosilicatelow O-fugacityFalls(9)finds(4)
'Fassaite'Augite Variety10InosilicateHi TFall(6)finds(4)
CristobaliteIMA Mineral5InosilicateLateFalls(4)find(1)
AenigmatiteIMA Mineral1InosilicateRareFall(1) Adzhi-Bogdo (stone)
'Ferroaugite'Augite variety1InosilicaterareFall(1) Chainpur (LL3.4)
FerrosiliteIMA Mineral1Inosilicaterare Find(1)ALHA76004 (LL3.3)
KosmochlorIMA Mineral1InosilicaterareFind(1)Inman (L/LL3.4)
'Feldspar'Mineral Group55Tektosilicatelow O-fugacityFalls(32)finds(23)
'Plagioclase'Mineral Series49TektosilicateExpectedFalls(29)finds(20)
'K Feldspar'Min. Subgroup6TektosilicateLateFalls(6)
AnorthiteIMA Mineral11TektosilicateHi TFalls(7)finds(4)
NephelineIMA Mineral11TektosilicateOccasional accessoryFalls(8)finds(3)
AlbiteIMA Mineral9TektosilicateOccasional accessoryFalls(7)finds(2)
TridymiteIMA Mineral8TektosilicateLateFalls(4)finds(4)
SodaliteIMA Mineral7TektosilicateHydrationFalls(3)finds(4)
'Scapolite'Mineral Series5TektosilicaterareFall(2)finds(3)
OrthoclaseIMA Mineral4TektosilicateLateFalls(4)
QuartzIMA Mineral2TektosilicateLateFalls(2) Adzhi-Bogdo*; Bo Xian
'Smectite'Mineral Group4PhyllosilicateHydrationFalls(4)
'Biotite'Mineral Series1PhyllosilicateHydrationFall(1)Bo Xian (LL3.9)
MeliliteIMA Mineral4SorosilicateSi-poor settingFalls(2)finds(2)
'Gehlenite'Mineral Group2SorosilicaterareFalls(2) Sharps & Semarkona
RoedderiteIMA Mineral3CyclosilicaterareFalls(2)find(1)
MerrihueiteIMA Mineral1CyclosilicateInclusionFall(1)Mezö-Madaras (L3.7)
'Glass'Glass52Silicate*ShockFalls(29)finds(23)Ubiquitous
'Maskelynite'Glass6Silicate*ShockFalls(2)finds(4)
WEATHERATES
'Limonite'Generic Term24Fe-Hydrates WeatherateFalls(2)finds(22) Common in Finds
MaghemiteIMA Mineral2Hydrous oxideEarth&SkyFalls(2)Semarkona & Bishunpur
WüstiteIMA Mineral2oxideIn crustsFalls(2)Piancaldoli & Bo Xian
GoethiteIMA Mineral1Hydrous oxideWeatheratefind (1)Brownfield (1937) (H3.7)
HematiteIMA Mineral1OxideWeatheratefind(1)Inman (L/LL3.4)
PHASE_NAMEREGISTERNCHEMISTRYPROVENANCEFALL#FIND#HOSTS (1 or 2 or Many)

Abbreviation: Adzhi-Bogdo* = Adzhi-Bogdo (stone)

We now consider the individual mineralites, cohort by cohort.

Category: Cosmic Iron [ 8 mineralites]
Fe-Ni metal (82), Kamacite (55), Taenite (46), Tetrataenite (16), Plessite (8), Awaruite (2), Martensite (2), Antitaenite (1)

We expect that any moderate-sized specimen of an unweathered ordinary chondrite will contain (unoxidized) Fe-Ni metal. There is, however, at least one plausible exception. The LL chondrites usually have ~2 wt% Fe-Ni metal and this number is quite variable. The LL chondrites are more oxidized and even mildly hydrated at times so it is not clear whether vanishingly small amounts of Fe-Ni metal might not be present in a small subset of LL chondrites. Somewhat surprisingly, Fe-Ni metal is reported for all of the 35 UOC finds of this study, but only in 42 of the 47 falls. This is apparently due to the fact that we have reported all witnessed falls — including some very incompletely described meteorites.

Kamacite is reported in 55 UECs (67%). While experienced observers such as Ramdohr (1973) and Rubin (1990) report a much higher incidence rate of kamacite than is reported here in our more generic set of references, there are real difficulties in determining the presence of kamacite in UOCs. In many instances the Fe-Ni metal has been shock heated, mobilized, and widely dispersed into very small grains that may or may not have recrystallized. Two largely unresolved/partially resolved issues using only the data reported here is (1) whether kamacite is present in significant quantities in the great majority of LL-group UOCs and (2) the extent to which kamacite has been entirely weathered away in old finds.

Taenite is reported here in 46 UOCs (56%). Again, Ramdohr (1973) reports a much higher incidence rate of taenite [93 %] in the 14 UOCs in our ensemble which he observed. And again, there are also serious difficulties in determining the presence of taenite in UOCs. In many instances the Fe-Ni metal has been shock heated, mobilized, and widely dispersed into very small grains that may or may not have recrystallized. Two largely unresolved/partially resolved issues using only the data reported here so far are whether taenite is the primary Fe-Ni in significant quantities in the great majority of LL-group UOCs and the extent to which kamacite has been entirely weathered away in old finds. Taenite is reported from 30 falls and 16 finds within our ensemble (64% and 46%, respectively) which suggests that two largely unresolved/partially resolved issues using our data are (1) whether taenite is the primary Fe-Ni in significant quantities in the great majority of LL-group UOCs and (2) the extent to which kamacite has been entirely weathered away in old finds.

Tetrataenite is reported in 16 instances (19.5%). The presence of tetrataenite appears to be correlated with two important physical conditions. One, tetrataenite (Ni ≥ ~50 mol%) is more likely to crystallize in more Ni-rich Fe-Ni metal. Two, original Fe-Ni metal [unoxidized!] in chondritic assemblages is expected to have been Fe-rich so that the appearance of meteorites in tetrataenite is a prima facie indicator of disequilibrium. The first reports of tetrataenite are rich in petrographic details of the tetragonal symmetry of small tetrataenite crystals within a matrix of zoned taenite (So called 'cloudy taenite.). In addition, 'normal' taenite in iron meteorites [compositions generally within the 10-30 mol% Ni range] appears to be part of 'more' equilibrated Fe-Ni assemblages than the smaller chondritic assemblages. For example, Widmanstätten patterns are only infrequently observed in chondritic Fe-Ni metal. Two cautionary remarks. As tetrataenite was only recognized in 1979, it would not have been recorded as such in some of the older reports we have necessarily utilized here. On the other hand, in several of the earlier reports of tetrataenite both zoned and unzoned taenite were observed within the tetrataenite-bearing meteorites. Thus, while tetrataenite seems to be quite obviously underreported here we must also be chary of reports of tetrataenite sans taenite. At the very least, it would seem that some of these reports should be redone. It still appears, however, that its presence in 9 of 23 LL group chondrites (39%) is ~2 sigma above the 19.5% mean for our entire 82 UOC enesembble.

Plessite (8) is reported in 8 instances (<10%). Ramdohr (1973) recorded plessite in 4 of 14 meteorites considered here (~29%). It seem clear that plessite is underreported in our survey, but it also seems quite clear that plessite is seldom abundant in UOCs and usually either quite sparse or even absent from most UOCs.

Awaruite (2), a very Ni-rich Fe-Ni metal phase (Ni ~75 mol%) is reported here only in Semarkona (LL3.00) and Krymka (LL3.2). As both Semarkona (LL3.00) and Krymka (LL3.2) are unusually primitive meteorites of the LL-group, our suspicion that awaruite require unequilibrated Ni-rich metal seems confirmed. While its appearance in two LL chondrites might be coincidental, its absence from all 56 H and L UOCs reported here suggests that we may be on to something.

Martensite (2) is reported here 2 instances, highly shocked Barratta (L3.8;S4) and the unusual Zag (H3-6) melange. Its presence in chondrites appears to be mostly due to quick cooling of Fe-Ni metal that has been shock-heated during the late stages of the original homeworld formation or in subsequent impacts.

Antitaenite (1) is reported here only from the Adzhi-Bogdo (stone) LL3-6 chondrite. Antitaenite is a quite unusual phase. It has a definite crystal structure ['mirror-image' α-iron = chirally asymmetric kamacite] and a known chemical definition [identical to kamacite]. These two characteristics meet the crystallographic and planetological-cosmochemical requirements of both common sense and meteoritic science which are implied by the word mineral.

Category: Selected Elements and Metallic Alloys [N = 5 mineralites]
Copper (17), Mercury (2), Silver (1), Tungsten (1), Zhanghengite (1)

In contrast to the abundant Fe-Ni metal so characteristic of most meteorites, other 'free' [unoxidized] elements or alloys are occasionally found only in small quantities in meteorites. Copper is quite frequently present in small quantities, but normally requires a watchful eye to be detected. Ramdohr, who observed copper in 8 of the 14 UOCs reported here, and Rubin (1994) have made it clear that small amount of metallic copper are frequently present in ordinary chondrites. However, our records here do not yet allow us to add much to that story. [We will consider elemental carbon polymorphs along with frequently associated carbides in the next subsection.]

The reports of the 3 metallic elements (Mercury, Silver, Tungsten) and the even rarer Zhanghengite are, at some level surprising. Mercury is reported from both Didim and Tieschitz while Tungsten and Silver are both reported only from Krymka (LL3.2). Zhanghengite, an unusual Cu-Zn alloy, was discovered in the Bo Xian LL3.9 chondrite. Indeed, Zhanghengite is one of 4 minerals that are reported only from Bo Xian. As an unusually primitive LL3.2 chondrite Krymka might be expected to have more than the usual allotment of unusual phases. However, the presence of Graphite, rare Moissanite (SiC), Ni-rich Awaruite and Tetrahedrite as well as Tungsten and Silver suggests that Krymka's formational components may have included a significant 'stream' of an unusually reduced and metal-rich nebular region and/or planetismals. Cinnabar (HgS) and elemental Mercury are both reported here only from Didim (H3-5) and Tieschitz (H/L3.6) suggesting, perhaps, a common source of chalcophilic volatiles for these two meteorites.

Category: Carbon Polymorphs and Carbides [N = 5 mineralites]
Graphite (17), Diamond (11), Cohenite (5), Moissanite (3), Cliftonite (1)

Graphite is reported in 17 instances. The major upshot of these reports is that pockets of reduced carbon were intermingled with other more oxidized regions within the Solar Nebula. A rather simplified explanation is that the outflows of carbon stars and other red giants with C:O ratios > 1 were incompletely mingled with the more oxidized portions of the ancient star cloud which eventually produced the Solar Nebula. Poorly graphitized carbon is found in a number of carbonaceous and unequilibrated ordinary chondrites, but such imperfectly crystallized carbon is usually not reported on most individual Mineral Lists including those studied here.

Diamonds (11) are found in a number of meteorite venues. In some instances the diamonds are shock produced by intra-asteroidal collisions. More intriguing are the much smaller nano-diamonds found within carbonaceous chondrites and, occasionally, in the primitive UCOs. These 'stardust' diamonds are characterized by wildly non-solar isotopic ratios of inert gases and nitrogen trapped within the diamond grains.

Cohenite is reported in 5 instances. As cohenite is occasionally found in iron meteorites it is not that unremarkable that such a reduced carbon phase is associated with Fe-Ni metal in the UOCs.

Moissanite (SiC) is reported in 3 instances. Again, SiC is often observed in the outflows of certain Red Giants and was apparently preserved in highly reduced regions of the Solar Nebula. Our three instances cited here include 2 of the meteorites from the small 'mixed' H/L and L/LL groups [Tieschitz (H/L3.6) and Inman (L/LL3.4)] as well as the more normally classified 'Krymka' (LL3.2). Most of the natural moissanite grains are variants of the 6H and 15R polytypes (e.g., SiC in stardust has more than one minerallic expression). However, in most of the astrophysical and cosmochemical literature explicit mineralogical characteristics are not normally reported. One reason is that there has been some resistance to labeling such small minerals as 'official' minerals.

Cliftonite is reported here in a single UOC instances, the large Grady (1937) [H3.7] find. In this instance, the cliftonite is pseudomorphous after kamacite and may be an indicator of live carbon exchange within the Solar Nebula.

Category: Sulfides [N = 8 mineralites]
Troilite (73), Pentlandite (9), Isocubanite (5), Pyrrhotite (5), Cinnabar (2), Haxonite (2), Covelite (1), Daubréelite (1)

Sulfides, especially troilite, are expected in even the smallest ordinary chondrite. There are, however, several important constraints in the sources cited here. First, the presence of troilite is so unexceptional that its presence is not always explicitly reported. Secondly, in UOCs the sulfides are often dispersed by even relatively mild shock heating events into small aggregates and grains that cannot be readily assigned a precise mineralogical identity. Thirdly, in most moderately representative samples, troilite is not the only sulfide present. Thus an observer who knows that more than one sulfide is present, but does not know the precise mineralogical identity of one or more of the sulfides will apply the mineralogically 'neutral' term 'sulfides' to these almost certainly troilite-bearing aggragates. In these instances, the 'sulfides' — including troilite, normally, the 3rd or 4th most abundant phase in the meteorite — may be entirely missing from the Mindat Mineral List for the particular meteorite.

The three problems cited above apply to both falls and finds. However, for the frequently weathered finds there are additional problematics. A critical additional petrographic element receives scant attention in many sources. Many UOCs, particularly the LL3 chondrites, have components which experienced late oxidation and/or hydration events Thus are a number of mildly 'oxidized' sulfides — pentlandite, pyrrhotite, isocubanite, etc. — which have been present in preterrestrial UOC meteoroids and are also frequent terrestrial weatherates. Consequently and, especially, in UOCs we find individual meteorites where a sulfide appears both as a preterrestrial ('primary') phase and as a terrestrial weatherate. Of course, in very weathered meteorites, sulfides are partially or completely altered into water soluble sulfates which will eventually be lost to any remnants of the original meteorite. These sulfates — even if present — are usually not even mentioned in the sources cited here. We can only highlight a few of the ambiguities and problematics of weathered meteorites here. However, for individual meteorites references for their individual minerals are at the meteorite's Mindat location site.

Troilite is reported in 73 instances here (89%). We note that the percentages for falls 85.1% is unexpectedly lower than the 94.3% reported for finds [% = 40/47, 33/35, respectively]. This moderately anomalous result presumably follows from the fact that we have reported all UOC falls regardless of inventory completeness. Our ensemble of UOC finds has been preselected from meteorites subject to more than average mineralogical coverage.

Pentlandite is reported in 9 UOCs, 5 falls and 4 finds.
Isocubanite is reported in 5 UOCs, 1 fall — Mezö-Madaras (L3.7) — and 4 finds.
Pyrrhotite is reported in 5 UOCs, all falls.
Cinnabar is reported in 2 UOCs, Tieschitz (H/L3.6) and Didim, Turkey (H3-5)
Haxonite is reported in 2 UOCs, Semarkona (LL3.00) and Ngawi (LL3.6).
Covelite is reported only from Tieschitz (H/L3.6).
Daubréelite is reported only from Semarkona (LL3.00) and is most likely to be found in extremely reducing environments.

Category: Halides/Nitrides/Phosphides [N = 4 mineralites]
Halite (1), Nierite (3), Schreibersite (8), Nickelphosphide (1)

We have lumped these usually rare accessories into a single cohort set because none of them are abundant enough to merit individual subsections in this essay.

Halite is reported here only from Zag (H3-6). Preterrestrial halite is extremely rare in meteorites, but is most likely due to interactions between water and chlorapatite in ancient planetismals
Nierite is reported in 3 UOCs [Adrar 003 (L/LL3.10), Inman (L/LL3.4), Tieschitz (H/L3.6)]. Nierite in meteorites is always or almost always 'stardust'- ejecta from ancient supernovae and/or red giants
Schreibersite is reported in 8 UOCs including 7 falls.
Nickelphosphide is reported here only from Inman (L/LL3.4).

Category: Phosphates [N = 6 mineralites]
Merrillite (25), Apatite (22), Chlorapatite (14), Fluorapatite (1), Marićite (1), Panethite (1)

Merrillite and apatite are found in small quantities in most ordinary chondrites. In the meteorites reported here one or more phosphate minerals or mineral series are reported in 33 instances (23 falls and 10 finds). In 14 instances both apatite and merrillite are reported. In UOCs phosphates are frequently found as very small grains. Precise mineralogical determination of such phase requires both expertise and extra effort. The superb mineralogist Brian Mason would frequently mention that 'either merrillite or apatite is present' when he reported on a meteorite. Others of less skill or, perhaps, working only with a microprobe report merely the presence of 'phosphates' or 'Ca-rich phosphates.'

Merrillite, an anhydrous Ca-phosphate, is reported here in 25 UOCs (16 falls and 9 finds). Merrillite is often identified in detailed studies of the lead-bearing phosphate minerals used in Pb-Pb dating of the most ancient meteorites. There has been some convincing evidence (X-ray crystallography) that the merrillite in meteorites in meteorites is slitely different from terrestrial whitlockite of nearly identical composition. However, the author harbors his own suspicions that the differences may be critically dependent upon the normally more anhydrous conditions of meteoritic 'merrillite' formation than upon any essential per se differences between meteoritic 'merrillite' and terrestrial 'whitlockite.'

Apatite is reported here in 22 UOCs. Apart from the deviations encountered in martian meteorites and carbonaceous meteorites, apatite in most meteorites — including ordinary chondrites — is usually chlorapatite. The reason is simple. One, fluorapatite is rare because — relative to other volatiles that can be accommodated into the apatite crystal structure — fluorine is almost alway scarce in stony worlds whether they are planets or small asteroids. Secondly, the hydroxylapatite common in terrestrial apatites is quite rare in meteorites. Technically speaking, of course, given the natural variabilities which define the UOC petrologic types there are surely individual apatite grains within these and other UOCs with chlorapatite < 50 mol%. One suspects, however, that the great majority of the apatite grains are indeed chlorapatite.
Chlorapatite is reported here in 14 UOCs (8 falls and 6 finds).
Fluorapatite, Marićite and Panethite are each reported only from a single UOC. Marićite and Panethite are reported only from Bishunpur meteorite (LL3.15). Fluorapatite is here reported only from Krymka' (LL3.2). Indeed, fluorapatite appears to be extremely rare in all ordinary chondrites. It is present in the relic H chondrite, Brunflo, as an apparent weatherate created during 400 million years within what is now Ordovician limestone.

Category: Carbonates [N = 3 mineralites]
Calcite (2), Aragonite (1), Dolomite (1)

Carbonate minerals, when found in meteorites, are usually terrestrial weatherates — products of terrestrial alterations of the meteorites original pre-terrestrial assemblage. However, in some carbonaceous chondrites, Martian meteorites and — very occasionally — they are sometimes either indisputably or arguably preterrestrial. When many observers see or otherwise detect terrestrially generates carbonate mineralites in meteorites, these phases may be given abbreviated attention or even ignored. Thus, the carbonates referenced here are a very small set of 4 instances of 3 minerals. However, because of their very important genetic significance they are assigned here to a separate planetochemical cohort category. [Caliche, a generic term for carbonate-rich assemblages found in limestone weatherates, is briefly considered under the 'Weatherate' category.]

Calcite is reported here from two falls, Bo Xian (LL3.9) and Semarkona (LL3.00). The Bo Xian reference is in Chinese and it is unclear to this author whether the calcite is primary or a terrestrial weatherate.
Aragonite is reported here only from Dimmitt (H3.7), a large 200 kg find. It has also been reported from other meteorites, mostly carbonaceous chondrites and, occasionally, as a terrestrial weatherate (e.g.,Coahuila).
Dolomite is reported here only from Bo Xian (LL3.9). Among meteorites it is most frequently reported from CI1 and CM2 carbonaceous chondrite falls. However, it has also been reported as an inclusion in several equilibrated ordinary chondrites [Tysnes Island (H4), Leighton (H5), Plainview (1917) (H5), Shaw (L6/7)].

Category: Oxides [N = 12]
Chromite (50), Spinel (27), Ilmenite (24), Magnetite (20), Chromspinel (10), Hibonite (10), Perovskite (6), Corundum (5), Rutile (4), Aluminous Chromite (1), Magnesioferrite (1), Hercynite (1)

Oxides, including several spinel minerals and spinel varieties, are usually opaque in thin section. They can sometimes be recognized in situ using the microprobe and may also be identified by several other techniques. They are often most easily identified by the oil-immersion techniques of reflected light microscopy. Thus, chromite and ilmenite have been reported in 50 (61%) and 24 (29%) instances, respectively, of our 82 UOCs. However, when Ramdohr (1973) studied fourteen of these meteorites he was able to identify chromite and ilmenite in 14 (100%!) and 8 (57%) UOCs, respectively.

Chromite is reported from 50 UOCs. Chromite is ubiquitous in all types of ordinary chondrites and is stable under a wide range of conditions. Our population statistics — chromite is found in 29/47 (62%) of UOC falls and 22/35 (63%) of UOC finds suggest that chromite is more resistant to weathering than other meteoritic phases. Detailed studies such as those of Alan E. Rubin (2003, 2004) would perhaps allow us to make more robust statistical conclusions than those using only our assorted references. Our po

Spinel is reported from 27 UOCs. The various varieties of spinel do, however, suggest that a statistically robust and petrologically significant interpretation of spinel abundances is still well in the future.

Ilmenite is reported from 24 UOCs. Again, we suspect that it is probably present in small quantities in the great majority of UOCs.

Magnetite is reported from 20 UOCs. Magnetite is almost always present in fusion crusts where it is seldom reported. In ordinary chondrites it may be also be present either as a preterrestrial phase or, especially in older finds, as a product of terrestrial weathering — or both.

Chromspinel is reported from 10 UOCs. When chromspinel is found in addition to the standard (ferrous) chromite found in virtually all ordinary chondrites it is possible to calculate very useful closure temperatures for such meteorites.
Hibonite, a high temperature condensate in nebular environments, is reported from 10 UOCs.
Corundum is reported from 5 UOCs. Corundum is a high temperature condensate in nebular environments. In a few rare instances, tiny corundum grains have been identified as stardust.
Rutile is reported from 4 UOCs. It is often associated with ilmenite.
Aluminous Chromite (a.k.a, 'aluminian chromite'), an Al-rich variety of chromite, is reported here only from Krymka (LL3.2).
Hercynite, an Fe-bearing spinel, is reported here only from Dhajala (H3.8).
Magnesioferrite — which might be loosely described as a Mg-bearing 'magnetite' is another spinel reported here only from a single meteorite [Bo Xian (LL3.9)].

Category: Silicates [N = 37 mineralites in 7 Subcategories]Subcategories: Nesosilicates (5), Inosilicates (12),Tektosilicates (), Phyllosilicates (2), Sorosilicates (2), Cyclosilicates (2), Silicates* [Disordered Silicates] (2)

Nesosilicates (n= 5 mineralites)
Olivine (82), Forsterite (37), Fayalite (8), Zircon (2), Wadsleyite (1)

Olivine is present, by definition, in all 82 UOCs.
Forsterite is reported from 37 UOCs including 15 falls and 22 finds. Forsterite sensu stricto (extremely Fe-poor Olivine) — like enstatite — may represent a sample of the inner regions of the early Solar Nebula.
Fayalite is reported from 8 UOCs. Fe-rich olivine (Fa > 50 mol%) usually appears to be a late addition to accreting chondrites and has been interpreted as reflecting a 'stream' of late hydrous and oxidizing components which may have entered the accretion process only after planetismal formation in the early Solar System had begun in earnest.
Zircon is reported here only from Adzhi-Bogdo (stone) (LL3.6) and Northwest Africa (L3-6).
Wadsleyite, a high pressure polymorph of olivine is reported here only from Bo Xian (LL3.9).

Inosilicates (n= 12 mineralites).
Orthopyroxene (45), Clinopyroxene (42), Augite (27), Diopside (21), Pigeonite (16), Clinoenstatite (13), Enstatite (13), Fassaite (10), Cristobalite (5), Aenigmatite (1), Ferroaugite (1), Ferrosilite (1), Kosmochlor (1)

Orthopyroxene is reported from 45 UOCs including 26 falls and 19 finds.
Clinopyroxene is reported from 42 UOCs including 23 falls and 19 finds. In this work, the term 'Clinopyroxene' usually refers to Ca-poor varieties of the Clinopyroxene Subgroup (esp., 'clinobronzite' and 'clinohypersthene').
Augite is reported from 27 UOCs including 18 falls and 9 finds.
Diopside is reported from 21 UOCs. Moderately variable 'diopsidic' pyroxene with compositions near the boundaries of diopside and augite, proper, are usually reported here as 'diopside.'
Pigeonite is reported from 16 UOCs.
Clinoenstatite is reported from 13 UOCs.
Enstatite is reported from 13 UOCs. Extremely iron poor enstatite [sensu stricto, orthopyroxene w. En ≥ 90 mol%], appears to reflect a high temperature asteroidal 'building block' derived, perhaps, from the primeval inner solar system.
Fassaite is reported from 10 UOCs.
Cristobalite is reported from 5 UOCs including 3 LL3 falls. A late silica-rich component appears in a number of LL group inclusions.
Aenigmatite is reported here only from Adzhi-Bogdo (stone) (LL3.6).
Ferroaugite is reported here only from Chainpur (LL3.4).
Ferrosilite is reported here only from ALHA76004 (LL3.3).

Tektosilicates (n= 11 mineralites).
Feldspar (55), Plagioclase (49), Anorthite (11), Nepheline (11), Albite (9), Tridymite (8), Sodalite (7), Scapolite (5), Orthoclase (4), Quartz (2), Kosmochlor (1)

Feldspar is reported from 55 UOCs including 32 falls and 23 finds. However, a significant orthoclase component (Or ≥ 10 mol%) is only occasionally reported.
Plagioclase is reported from 49 UOCs including 29 falls and 20 finds.
Anorthite is reported from 11 UOCs. Anorthite, sensu stricto w. An ≥ 90 mol%, appears to reflect a higher temperature mode of formation than the albitic plagioclase which dominates the feldspathic mineralogy of all ordinary chondrites.
Nepheline is reported from 11 UOCs.
Albite is reported from 9 UOCs.
Tridymite is reported from 8 UOCs. Si-rich inclusions may represent late additions to ordinary chondrites.
Sodalite is reported from 7 UOCs.
Scapolite is reported from 5 UOCs including 4 LL3 chondrites.
K-Feldspar (including orthoclase) is reported from 5 UOCs including 4 LL3 chondrites. Other reports of 'Feldspar' may
Orthoclase is explicitly reported from 3 UOCs.
Quartz is reported from 2 UOCs, Adzhi-Bogdo (stone) (LL3.6) & Bo Xian (LL3.9).
Kosmochlor is reported here only from Inman (L/L3.4).

Phyllosilicates (n= 2 mineralites):
Smectite (4), Biotite (1)

Smectite is reported here from 4 falls.
Biotite is reported here only from Bo Xian (LL3.9).

Sorosilicates (n= 2 mineralites):
Melilite (4), Gehlenite (2)

Melilite is reported from 4 UOCs.
Gehlenite is reported only from Sharps (H3.4) and Semarkona (LL3.00)

Cyclosilicates (n= 2 mineralites):
Roedderite (3), Merrihueite (1)

Roedderite is reported here from ALHA77278, Bo Xian, and Mezö-Madaras.
Merrihueite is reported here only from Mezö-Madaras (L3.7) where it was discovered.

Silicates* — Disordered silicates or glasses (n= 2 mineralites).
Glass (51); Maskelynite (6)

Glass — Primary Glass, mostly of silicate composition, is a defining characteristic of UOCs and has been explicitly reported for 52 UOCs including 29 falls and 23 finds. The glass almost always has a significant plagioclase-composition component is which is, however, inconsistently reported.
Maskelynite, glass of normative plagioclase composition, is explicitly reported for 6 UOCs. It is, however, seriously underreported here as plagioclase is much more easily vitrified than olivine and the pyroxenes.

Category: Weatherates [N = 6]
Limonite (24), Maghemite (2), Wüstite (2), Caliche ( 1), Goethite (1), Hematite (1)

Our weatherate category is intended to highlite those mineralites that — when found in meteorites —are usually the products of terrestrial weathering. However, the four IMA minerals in our list — Maghemite, Wüstite, Goethite, and Hematite — may occasionally be present as pre-terrestrial phases. In these instances, oxidation and/or hydration may have occurred on an earth-bound meteoroid or on an original parent body (OPB). In other word, the weathering occurred in an extraterrestrial environment. This issue is quite central in the study of martian meteorites and primitive carbonaceous chondrites where the same mineral may appear in the same meteorite as products of both preterrestrial and post-terrestrial processes. And, the issue also occasionally becomes a significant problematic in understanding the formation of UOC mineralites.

Limonite is reported in 24 UOCs. Limonite in meteorites is a generic term for the aggregates of miscellaneous hydrous iron oxides produced mostly by the terrestrial weathering of the Fe-Ni metal and iron sulfides. Its primary mineral is usually goethite and is normally accompanied by additional phases such as maghemite, hematite, and less organized 'minerals.' The occurrence of Limonite in two witnessed falls, Bremervörde (H/L3.9) and Heyetang (L3.4), may be due to imperfect curation and/or the acquisition of additional fragments in the weeks and months following the immediate acquisition of one or more freshly fallen specimens.

Maghemite is reported from 2 UOC falls, Semarkona (LL3.00) and Bishunpur (LL3.15).
Wüstite is reported in both Piancaldoli (LL3.4) and Bo Xian (LL3.9). It is a frequent component of the fusion crust. It is produced during the very speedy melting and incomplete oxidation of the meteorite's 'skin' during its very brief atmospheric entry.
Caliche, another generic term, is reported here only for Northwest Africa 869 (L3-6).
Goethite is reported here only in an H3.7 find, Brownfield (1937).
Hematite is reported here only in Inman (L/LL3.4), a 1966 find.

Section V: Directions in UOC Research


This survey has been a strictly provisional report. Information about the mineralogy of these meteorites may be in the nooks and crannies of publicly available resources, in foreign languages or in databases which are not available to the public. Perhaps, however, it will be useful for readers because it brings together in one place and in an accessible venue information about the mineralogy of the intriguing unequilibrated meteorites. And, of course, other Mindat users are or will improve the mineral lists for these particular inventories. I will add here some suggestions that might enhance the useful role that mineralogy will play in future research about the Unequilibrated Ordinary Chondrites. The author also envisions the idea that after finishing a small project related to Paul Ramdohr's treatment of opaque minerals in ordinary chondrites that it might be useful to revisit the issues broached here. In view of his advancing age, however, it seems wiser to put these ideas out for discussion as they stand.

The three major classes of Unequilibrated Ordinary Chondrites (UOCs) are so similar to in bulk chemistry, oxygen isotopes, and general oxidation levels that it is clearly reasonable to believe that the three major classes of Equilibrated Ordinary Chondrites (EOCs) were formed primarily by the aggregation and subsequent thermal metamorphism (presumably driven in large measure by the radioactive decay of Al-26 and other short-lived radioactive constituents) of UOC materials. The UOCs themselves, however, contained a large number of exotic components whose former presence in the EOCs have been largely erased in the EOC parent bodies by that metamorphism. [Whether the UOCs are themselves former constituents of the EOC parent bodies surface layers or interiors is a question that we do not need to address here.] What seems, in fact, most significant about the UOC total inventory are the suggestions here that (1) the raw materials of the H-, L-, and LL-groups included material from quite divergent oxidation-reduction regimes and (2) that the LL3 UOCs, in particular, appear to be loaded with diverse exotic materials that are well outside the norm of the H and L groups.

One fundamental question about the L- and LL-groups is whether, in the main, they constitute fragments of a single putative original parent body (OPB) or whether they are (mostly) fragments of two OPBs. Whether, they can or cannot be construed as being derived in large part from one or two OPBs, an additional question is whether and how material might have been exchanged between any major accreting bodies and and during subsequent later collisional additions. The suggestion has been made that the LL-group seems to have been marked by prominent late hydration-oxidation events that contrast quite strongly with the L-group's own differentiation from the H-group. [What are the implication's of Prior's rules?] More complete collisional chronologies and isotopic studies will be essential components in advancing our understanding of these issues. However, it is also clear that relying on chemical systematics alone is a fool's errand. Each of the large and diverse set of minerals and mineralites in UOCs record individual events in the complex gravitationally driven, collisionally-marked interactions that over the past 4.7 billion years as nebular gases and solids were first transformed into planetismals and asteroids before fragments of them were then re-dispersed into the sun, the solar system, and interstellar space. A small fraction of a fraction of those populations have struck the earth where a minute fraction of a fraction are now recognized as UOC meteorites. The constituent mineral groups, minerals, mineral varieties, mineral-intergrowths, and glasses — including the small, minor constituents not necessary for gross classification — require more attention than they are getting.

Of course, meteoriticists will never be able to reserve the available meteorites for purely scientific study. However, we can demand that a recognized label of a superior classification would include a reasonable estimate of the relative ratios of clinopyroxene/orthopyroxene, kamacite/taenite, and plagioclase/glass. And, as ordinary chondrites almost always contain a few mineralogical oddities and inclusions, we should demand that before a private vendor sets out sell his meteorite at $1—$1000 per kilogram for a 20—100 kg meteorite that a significantly large portion should be given a thorough petrographic, mineralogical, geochemical, and isotopic study before returning almost all of the sample to the owner. And, along the way, we need to employ a mineralogical language which is consistent with the planetological and planetochemical objectives of contemporary meteoritics.

Bibliography


The bibliographical sources here are those most immediately relevant to this essay. Specific references for each listed IMA mineral and mineralogical items on 'Mineral Lists' for Mindat-listed meteorites are found at the Mindat meteorite location site. In addition, The Meteoritical Bulletin Database provides additional reference links for most meteorites.

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Appendix: Neologisms, Meteoritical Terms & Abbreviations, Planetochemical Nuances


The Key Term: Planetochemical (neologism)

The chemistry of meteorites is a product of (1) astronomical events which (2) produced Solar System planetary bodies whose fragments have reached the earth where subsequently (3) they — when recovered promptly — have experienced minimal alteration within their interiors. These events have resulted, thus, in cosmochemical, planetochemical, and (mildly) geochemical alteration. To our knowledge, however, meteorites are naturally described by human beings whose chemical language is necessarily a 'geochemical' language. Furthermore, meteorites are usually rich in silicate minerals produced, in many instances by processes similar to the 'geophysical' dynamics that produce the 'geochemical' signatures present in terrestrial rocks and minerals. Nevertheless, the central question in contemporary meteoritics is not how meteorites are similar to the earth — incredibly intresting and important as that question continues to be. The central question in meteoritics is 'Where in the sun's planetary system did meteorites originate?' To answer that question we must be fundamentally concerned with the planetochemical signatures of planetological processes. That inquiry may demand an explicitly planetochemical vocabulary at almost any level of inquiry.

Other Essential Terms and Abbreviations [Multiple registers]
'Restrictions' here are protocols adopted by the author which are frequently in keeping with best usage within the meteoritical community and which, more importantly, reduce planetochemical ambiguities fundamental to meteoritic science.

TERMS (ABBR.) — DEFINITION
Albite (restriction) — Albite is, when possible, restricted to plagioclase of composition Ab ≥ 90 mol%
Anorthite (restriction) — Anorthite is, when possible, restricted to plagioclase of composition An ≥ 90 mol%
Clinopyroxene (restriction) — Clinopyroxene, here, is the preferred term for Ca-poor, moderately Mg-rich clinopyroxenes (older clinobronzite and clinohypersthene).
Enstatite (restriction) — To minimize ambiguities, the term 'enstatite' is, whenever possible, restricted to unusually Mg-rich, Fe-poor Orthopyroxenes (En≥90 mol% or Fs <10 mol%).
Equilibrated Ordinary Chondrite (EOC) — An ordinary chondrite with equilibrated olivine of uniform composition accompanied by pyroxene which is very nearly or completely equilibrated. Primary glass is missing. [An Ordinary Chondrite of Petrologic Types 4-7]
Forsterite (restriction) — To minimize ambiguities, the term 'Forsterite' is restricted to unusually Mg-rich, Fe-poor Olivines (Fo≥90 mol% or, equivalently, Fa <10 mol%)
Kamacite ('α-iron') — The primary phase within Fe-Ni metal of both stony and iron-rich meteorites is the mineral kamacite. Today, it is still the predominant Fe-rich mineral which any terrestrial geologist will encounter on the planet earth whether he or she is looking for iron ores or meteorites on the surface of the earth or deep within a mine. To the meteoriticist, kamacite is not — historically or practically — a 'variety' of iron. It is the most common form of natural metallic iron which we will find anywhere near the surface of any planets or asteroids in the next few centuries.
[Disciplinary dialect.Some members of the meteoritical community refer to any form of iron-dominated body-centered cubic iron in meteorites as kamacite. In those rare instances of secondary iron in meteorites — unoxidized iron with < 2% nickel which has lost its obvious fundamental extraterrestrial signatures — the author prefers to label simply as iron.]
Fe-Ni Metal, short definition — Preferred term in the meteoritical literature for meteoritic iron-invariably-accompanied-by-nickel and other accompanying siderophiles characteristic of extraterrestrial origins.
Fe-Ni Metal, a mildly more technical definition — Primary unoxidized or metallic iron accompanied by nickel, cobalt, chromium, phosphorus and other siderophiles. The nickel content varies, but is usually in the 5-30% range. Cobalt is also slitely variable but almost always in the 0.3-3.0% range. The abundances of associated minor elements such as phosphorus and chromium and even less abundant siderophiles (Palladium-group and Platinum-group elements) are characteristically a few orders of magnitude greater than the abundances normally found in terrestrial crustal rocks. kamacite is normally the major constituent of a meteorite's Fe-Ni metal.
Feldspar (preference) — When the composition is known, the feldspar is the preferred term for plagioclase feldspar with Or ≥ 10 mol% or Or≥An.
Mineralite — A collective term for mineralogically significant items, including — especially — minerals, mineral groups, mineral varietes, and chemically-defined terms important for meteoritic inquiry.
Orthopyroxene (preference) — Orthopyroxene is here the preferred term for Ca-poor, moderately Mg-rich Orthopyroxene (including, e.g., older varieties Bronzite and Hypersthene …)
Planetochemical (neologism) — Of chemistry especially directed towards understanding of the chemical signatures of planetary processes.
Plagioclase (Preferred Usage) — Plagioclase is the preferred term for non-endmember plagioclase (An or Ab <90 mol%). The intermediate varieties of plagioclase (bytownite, labradorite, andesine, and oligoclase), are tallied here as instances of Plagioclase.
Stardust — (Usually) Tiny pre-solar grains, mineralites with isotopic and elemental signatures of stars and/or gas clouds present before the birth of the Solar System.
Unequilibrated Ordinary Chondrite (UOC) — An ordinary chondrite with unequilibrated (variable) olivine and pyroxene and primary glass. [An Ordinary Chondrite of Petrologic Type 3]
Weatherate — A mineralite or mineralite that — when found in a meteorite — is usually the product of terrestrial weathering. The adjective 'terrestrial' is often implied. However, in carbonaceous chondrites, martian meteorites, and some UOCs such phases may be of preterrestrial origin.




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