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Andalusite
Posted by Rock Currier
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Andalusite May 15, 2009 08:40PM |
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Can you help make this a better article? What good localities have we missed? Can you supply pictures of better specimens than those we show here? Can you give us more and better information about the specimens from these localities? Can you supply better geological or historical information on these localities?
Andalusite
Al2SiO5
First Draft
Andalusite is a relatively common mineral most often found in low to medium grade metamorphic rocks. It is polymorph with kyanite and sillimanite. Andalusite often occurs together with one of these minerals, but rarely with both of them. Cordierite, staurolite , micas and garnets are other common associates of andalusite. Andalusite is formed in low pressure/High temperature environments, and the typical environment will be in argillaceous sediments (i.e formed by clays or other fine grained sediment) in a contact aureole around an intrusion, but it is also often formed as a result of regional metamorphosis. It may also occur in other environments, such as quarts veins and dykes, granite pegmatites, as the result of metasomatic or pneumatolitic action ( chemical alteration due to influence from hydrothermal fluids or gases) or even in low pressure granites.
The crystals are normally prismatic with a square cross section, often with poor terminatons and of a pinksh/brownish colour. They can be quite large, crystals up to 50 cm have been reported from several localities, also some not presented in this article. The crystals are normally translucent to opaque, but transparant crystals and river pebbles has been found in Brazil and Sri Lanka. They make beautiful and attractive gems. Faceted stones up 75 to 100 carats from Brazil are known although faceted stones over 20 carats are extremely rare.
A variety of andalusite that also are used to make jewellery, amulets is chiastolite, This variety is named after the greek letter "chi" (χ) due to cross formed inclusions along the C-axis of the crystals. Chiastolite is formed in the early stages of metamorphosis within the andalusite stability area. After the initial formation of anhedral andalusite grains, but the crystals rapidly get a prismatic outline, pushing aside enclosed matter to form the chiastolite pattern. In a more advances metamorphic grade, the andalusite becomes clear of inclusions.
Andalusite will normally have small amounts of Fe3+ replacing Al in the crystal structure, and sometimes also Mn3+. The content of ferric iron is normally low (rarely more than 5wt% Fe2O3 ), whereas the Mn3+ can be significant, or even dominant (Mn3+>Al). Specimens that are Mn3+ dominant, qualifies as a separate mineral species, kanonaite, and a complete solid solution series exists between the two minerals. The intermediate members of the series, Mn-rich andalusite has a green colour and has it's own varietal name, viridine.
Andalusite is often pseudomorphosed to other minerals, due to changes in the metamorphic grade after andalusite crystals have formed. An increase in metamorphic grade will form kyanite or sillimanite pseudomorphs, and even kyanite after chiastolite with the cross pattern intact are known from the Kola peninsula in Russia. Also mica and pyrophyllite pseudomorphs after andalusite is common. Andalusite is however quite resistant to moth chemical and mechanical weathering at ambient conditions, and may concentrate in sediments. In Transvaal in the Republic of South Africa, millions of tons of andalusite pebbles have concentrated in sediments and are mined as a raw material for producing refractory products used in the metallurgical industry, building materials industry, and others due to it's high temperature volume stability, mechanical strength, thermal shock resistance and creep resistance,
The Transvaal andalusite locality may occationally produce crystals up yo 10cm, but it is not yet included in this artcle as there are no photos uploaded to Mindat. With a few exceptions, only localities with photos included in the article. There are undoubtably localities that could have been included in the article, this includes some of th classic German localities, several Russian localities that produce(d?) large well formed crystals, as well as other localities
Andalusite
Australia,
South Australia, Olary Province, Mount Howden
Andalusite of the chiastolite variety was first described from here in 1902, and soon earned a reputation of producing some of the worlds best chiastolite specimens. Older literature even use the name "howdenite" for andalusite from here. Mt; Howden, itself is not that impressive, being more of a small hill than a mountain, lies ten miles north of Bimbowrie, South Australia.
Anderson (1902) gave the first description of the Mount Howden chiastolite: "The crystals are distinguished by large size, they show the characteristic markings very distinctly, and some exhibit features which, so far as I know, have not hitherto been described. According to Mr. Howden, the Bimbowrie mineral occurs either embedded in argillaceous schist, or as rolled pebbles, along with quartz, jasper, aventurine, etc. Towards the surface, where atmospheric influences are at work, the crystals are fairly easy of extraction, and all the more perfect specimens obtained were weathered out. Mr. Howden states that embedded crystals occur with the long axis parallel to the foliation. The crystals are columnar in habit, elongated in the direction of the vertical axis.
Some specimens reach a length of five to six inches, and one, has a diameter of about two inches. None show well defined crystal outlines, the edges being more or less rounded. When complete the crystals taper to either end, the relation of length to breadth being about 4 : 1. They have a brownish crust, and the surface is spangled with flakes of mica. The colour of a cut crystal varies, grey predominating, but some are reddish brown, and some have a pinkish tinge."
The weathered out crystals have all been picked, and today only those frozen in rock remains. Collecting on the Bimbowrie Station (including the Mt Howden locality) is no longer allowed as it has been turned into a National Park.
In geologic terms, this locality belongs to the Alconie Formation (formerly Alconie Pelite, Conor 2000a), which consist of a lower aluminous pelite unit and an upper dark grey, fine-grained, graphitic psammopelite. The basal unit is andalusite-rich and contains large chiastolite porphyroblasts in several outcrops.
Andalusite can also be found in other metapelite formations belonging to the Curnamona and Strathearn Groups, and consequently good localities are still accessible in the area, Dart (2011) highlights the neighbouring property of Kalabity, where good samples can be found on the hill behind the shearing shed and further north along the valley of Calico Creek.
references:
Anderson, C., (1902): On some specimens of Chiastolite from Bimbowrie, South Australia. Records of the Australian Museum 4(7): 298–302
Trevor Dart (ed) (2011): Mineral Profile – Andalusite, kyanite and sillimanite, The Newsletter of The Broken Hill Mineral Club Inc., Volume 12, Issue 1
Conor, C. H. H., (2002):. Geology of the Olary Domain, Curnamona Province, South Australia, Part 1: Geology. PIRSA Report Book 2002/015
Colin H.H. Conor (2000): Definition of major sedimentary and igneous units of the Olary Domain, Curnamona Province. MESA Journal Vol 19
Andalusite
Australia
Western Australia, Yalgoo Shire, Paynes Find
Paynes Find is a gold prospect located in a historically important gold region within the Southern Murchison Province of the Archaen Yilgarn block. On a regional scale, the geology of all these mining areas a quite similar and is dominated by granite intrusions and patches of rocks belonging to the Yalgoo-Singleton greenstone belt. The greenstone belt contains both metasedimentary and metavolcanic rocks. Andalusite is found in areas where metapelitic rocks are influenced by heat from the granite intrusions. According to the literature, andalusite is rather common in this remote area. It is hard to say how good the specimens get, as the search for gold easily overshadows the potential for andalusite specimens.
references:
Paynes Find Gold Limited(2011): Stage 2 planned drilling area, ASX Release
Catherine V. Spaggiari, Robert T. Pidgeon, Simon A. Wilde (2007): The Jack Hills greenstone belt, Western Australia Part 2: Lithological relationships and implications for the deposition of ≥4.0 Ga detrital zircons, Precambrian Research vol 155 pp261–286
Andalusite
Austria,
Tyrol, North Tyrol, Sellrain valley, Lüsens valley (Lisens valley; Lüsens alp; Lisens alp)
The “andalusite” from Linsen occurs in pegmatite-like quarz and feldspar lenses in what is termed “mineral-rich micaschists” by several authors. These lenses can become multiple meters wide and tens of meters long. Schmidegg(1949) describes one of the main localities near Lisens where “andalusite” occurs as crystals up to and exceeding 20 cm in a 30cm wide border zone in a large quartz lens . The distribution of andalusite is not uniform, and locally the lens was quite rich in “andalusite”crystals. He also mentions multiple other similar lenses in the continuation of the main lens, but that it was impossible to find many of the “andalusite” localities mentioned in older litereature in the area. The earliest reference I have found on Linsens andalusite is von Leonard (1843), but already then it appears that this locality was widely known and specimens distributed to museums around Europe.
Both Schmidegg and Hoinkes et.al (1982) have investigated these crystals closer and found that they often are fully or partly pseudomorphosed to kyanite and pyrophyllite.
The rocks on this locality belongs to the Ötztal-Complex, which are Variscan (390-295 Ma) rocks, metamorphosed to peak conditions (amphibolite/eclogite facies) before the Alpine orogeny. A systematic regional zonation of the AI2Si05 polymorphs, kyanite, sillimanite and andalusite has been observed in metapelites a within the Ötztal-Complex. The Lisens andalusite localities lies in the sillimanite zone and it is believed that the andalusite bearing quartz/feldspar lenses has formed post peak-conditions in the same Variscan event, as is also the kyanite/ pyrophyllite pseudomorphs.
references:
Gustav von Leonard (1843): Handwörterbuch der topographischen Mineralogie, Akademische Verlags-Handlung von J.C.B. Mohr
G.Hoinkes, F. Purtscheller, R. Tessadri (1982): Polymetamorphose im Ostalpin westlich der Tauern Ötztaler Masse, Schneeberger Zug, Brennermesozoikum, Geol. Paläont. Mitt. Innsbruck Band 12, S 95-113
Joachim Schweigl (1995): Neue geochronologische und isotopengeologische Daten zur voralpidischen Entwicklungsgeschichte im Ötztalkristallin (Ostalpen), Jahrbuch der Geologischen Bundesanstalt, Band 138 Heft 1 S. 131–149
Jürgen Konzett, Georg Hoinkes, Peter Tropper (2003): 5th workshop of alpine geological studies, filed trip guide E4, Alpine metamorphism in the Schneeberg Complex and neighboring units (immediate vicinity of Obergurgl), Geol. Paläont. Mitt. Innsbruck Band 26, S 21-45.
Andalusite
Austria
Vorarlberg, Montafon, Gargellen valley, Vergalda, Heimspitze
Andalusite is found near the peak of the Heimspitze in a mica schist belonging to the Silvretta crystalline complex. The locality has been known since late in the 19th century. Rompel (1894) describes dark red andalusite crystals covered with tiny flakes of light colored mica. The individual crystals may reach 9 cm, but generally with poor terminations.
References:
J. Rompel (1894): Ein neuer Fundort for Andalusit auf der Heimspitze In Vorarlberg, Tschermaks Mitt., Bd. 14, s 565—568
Otto Reithofer(1937): Über das Vorkommen von Andalusit in Vorarlberg, Verhandlungen der Geologischen Bundesanstalt.s 191-192
Andalusite
Belgium,
Liège Province, Stavelot Massif, Lienne valley, Lierneux, Petit-Sart, Thier del Preu quarry (Thier del Preux; Tiers del Preu)
Thier del Preu is one of the localities for the Mn-rich andalusite, viridine in the Stavelot massif in Belgium. The mineral occurs in Ordovician Mn-rich metasedimentary slates belonging to the "Sm2c" unit (refered to as the "Colanhan" unit by Geukens, other authors use different naming conventions). The Thier del Preu quarry and is one of the few places where this formation is exposed.
The andalusite occurs as green crystalline masses and crystal groups to more than 5cm in brecciated quartz veins ( bréchoïdes). The andalusite occurs with, and is sometimes partly replaced by green pyrophyllite. Andalusite may also be found as small crystals, often sericitized in the slate.
References:
Michel Blondieau (2005): Les gisements minéraux du Salmien dans le Massif de Stavelot
Fernand Geukens (2008): La carte géologique de Bra – Lirerneux
Kanonaite, Andalusite
Belgium,
Luxembourg Province, Stavelot Massif, Vielsalm, Salmchâteau, Le Coreux
Kanonaite is a mineral where Mn3+ is the dominant element in the octaedral 3+ position in the andalusite molecule, thus justifying the approval as a separate mineral species. Andalusite frequently contains some Mn3+ (viridine variety) but rarly in sufficient quantities to qualify as kanonaite.
At Le Coreux, kanonaite occurs as thin discontinuous veins in both quartz veins and in the phyllite host rock. The individual crystals can be up to several mm in size. The crystals in the quartz veins are near end member kanonaite, except that it is sometimes partially decomposed to a mixture of muscovite and Mn-oxides. The “kanonaite” in the phyllite is of variable composition, often zoned from an andalusite (var viridine) core with Mn-dominant kanonaite rims.
As Mn3+ stabilizes the andalusite molecule at lower temperature, it is believed that the crystallization of the kanonaite has taken place after peak metamorphic conditions, which is consistent with its occurrence as rims in the phyllite and near end-member composition in the late forming quartz veins.
The Le Coreux outcrop is located about 1 km north of Salmchateau. It consists of very dark violet and hard Ordovician metapelites (phyllite) belonging to the “Sm2” formation of the Stavelot massif. These rocks which underwent low-grade metamorphism during late Hercynian times. The original pelites were unusually rich in highly oxidized manganese and contain a wealth of manganese minerals. They are particularly enriched within the late quartz veins and have been studied for over a century.
references
Michel Blondieau (2005): Les gisements minéraux du Salmien dans le Massif de Stavelot
Schreyer W., Bernhardt H.-J., Fransolet A.-M. and Armbruster T. (2004): End-member ferrian kanonaite: an andalusite phase with one Al fully replaced by (Mn, Fe)3+ in a quartz vein from the Ardennes mountains, Belgium, and its origin. Contributions to Mineralogy and Petrology, vol 147, pp 276-287.
Andalusite
Brazil
Bahia, Chapada Diamantina, Serra da Mangabeira.
"Here in pockets in the bed rock are concentrated pockets of gravel that are rich in pebbles of cassiterite but sometimes also contain small pebbles of Andalusite, some of it gem grade. The gem rough found here are almost always rounded translucent to transparent pebbles that are strongly pleochroic; yellow brown to yellow green. Rarely stones are found that are an intense green and are given the varietal name of viridine. The color is caused by manganese. These gem gravels will rarely produce a stone of more than a cm in size. Gem pebbles are also reported to have come from near Santa Tereza in Espirito Santo State. The small gem crystal pictured here was simply labeled Bahia but it is probably from the Chapada Diamantina area. This little crystal would easily cost you $500 to $1000 if you are lucky. Chapada Diamantina is a quartzitic highland plateau running north and south and located east of Salvador in central Bahia. This area is known as the Serra da Mangabeira and located near the small towns of Livramento do Brumado and Paramirim which are 66.5 & 130 km respectively north of Brumado."1
The andalusite found in the placers in the Livramento do Brumado and Paramirim area originates from metapelitic rocks belonging to the Contendas-Mirante volcano-sedimentary belt. The Contendas-Mirante volcano-sedimentary belt is a approximately 190 km long and 65 km wide North-South synform. The belt itself is made up of supracrustal formations, metamorphosed in the westem part of the belt in the greenschist facies and progressively changing eastwards to amphibolite facies.
Andalusite is together with cordierite a dominant mineral in the metapelitic (andalusite or mica) schists and the gem varieties are originates from hydrothermal quartz veins within these schists.
The gem andalusite are extracted as water worn pebbles from placers within this belt, and occurs with quartz, kyanite, diaspore, zincian staurolite, cassiterite, gold, bahianite and eskolaite , the metal ores originating from igneous intrusions. White(1974) locates 34 placers worked for cassiterite in the triangle between Rio de Contas, Livramento do Brumado and Paramirim. These placers has been worked since the 1930-ties.
References:
1Rock Currier
Max G. White(1974): Tin resources of Brazil, USGS Open-File Report: 74-333
Moacyr M. Marinho, Pierre Sabate, Johildo Barbosa (1993): The Contendas-Mirante Volcano-sedimentary belt, Boletim IG-USP. Publicação Especial, vol 15:pp37-72
Paul B Moore, Carlos Do Prado Barbosa, Richard Gaines (1978): Bahianite, Sb3A15014(OH)2, a new species, Mineralogical Magazine Vol 4002 pp179-82
Andalusite
Brazil,
Bahia, Vitória da Conquista, Recruta Farm
The andalusite var viridine from Vitória da Conquista probably originates from a quartz vein in a meta pellitic schist in the Contendas-Mirante Volcano-sedimentary belt.
Andalusite
Brazil,
Espírito Santo
Andalusite is found in an area some 15km wide and 40km in length near the town of Santa Teresa in the state of Espirito Santo. The gem material is rarely found in crystals with good form and most of the gemmy material is found as water-wornpebbles. The Brazilian stones usually show a very strong flesh-red andolive-green pleochroism, which is especially well brought out when thestones are cut with the table facet nearly at right angles to the verticalaxis of the crystal.
More detailed information should be available in Luiz Carlos Malta Cantarella (2003): Aspectos Geológicos,mineralógicos e gemológicos da Andaluzita de Santa Teresa, estado do Espírito Santa, and P. K. Ruplinger(1983) Topaz and Andalusite Mining in Brazil Journal of gemnology ; vol. 18, no. 7, 1983. I would appreciate if someone could send me a pdf copy.
Reference:
Michael O’Donoghue (ed.)(2006): Gems Their Sources, Descriptions and Identification Sixth Edition
Andalusite
Brazil
Minas Gerais, Cruzeiro Novo (county), Santa Maria.
“Sometimes in gem color and transparency, nice crystals.,”1 . Green or tan transparent crystals, mostly single but sharp and gemmy up to 5 cm were found but most were less than 2 cm. The best of these transparent crystals were from Minas Gerais, and if you want one you will have to be satisfied with a thumbnail size specimen. It could cost you several hundred dollars or more if you can find one.
1 Mineralogical Record, Vol. 2, 1971, p10.
Andalusite
Brazil,
Minas Gerais, Jequitinhonha valley, Itinga
Andalusite occurs as a common rock forming mineral in metapelitic schists and shales (Salinas shales) several places in the northern parts of Minas Gerais. Small crystal clusters are known from these rocks, but the best crystals are formed in quartz veins in andalusite bearing mica schists, where crystals exceeding 7 cm are known. Some of the smaller crystals may also be transparent.The localities in Minas Gerais are, together with the occurances near Santa Teresa, the richest source of gem andalusite. The gem andalusite are also known from river placers.
The locality information given on some of these specimens are often inaccurate, partly it appears to protect the locality, partly because the retrieval of the specimens has been illegal and partly because the information has been lost somewhere between the finder and the line of mineral traders. Already Heidinger(1844) who investigated a small quantity of gemmy, partly water worn crystals expressed some frustration over the lack of accurate locality information: “ Die…registrirte Localitȁt ist Rio dos Americanos in Minas Novas in der capitanie von Minas Geraes, eine sehr ausgedehnte Localitȁt, da sie eine ganzen Fluss begreift”.
The andalusite from here are sometimes partly replased by pyrophyllite.
References:
W.Heidinger(1844): Ȕber den durchsichtigen Andalusite aus Minas novas Brasilien, Aus den Abhanellungen der k.bȍhm. Gesellschaft der Wissenschaften (V.Folge, Band 3)
Silva, Cassio Roberto da (2011): Avaliação do risco geológico à exposição de elementos químicos à saúde ambiental, na região de Araçuaí-Itinga, Minas Gerais – Brasil. Tese (Doutorado em Geologia) – Universidade Federal do Rio de Janeiro, Instituto de Geociências, Programa de Pós-Graduação em Geologia
Rui L.B.P. Monteiro, Othon H. Leonardos and Jose Marques Correi A-Neves(1990): An Epigenetic origin for the new scheelite and wolframite occurrences in the middle Jequitinhonha valley, Minas Gerais, Brazil, Revista Brasileira de Geociências 20(l-4):68-74
Andalusite
Brazil,
Minas Gerais, Jequitinhonha valley, Itinga, Jenipapo district
Andalusite
China,
Henan Province, Nanyang Prefecture, Xixia Co., Sangping Mine (Xixia Mine)
The Henan Xixia Andalusite Mine in Henan Province is a producer of andalusite for industrial purposes. It is believed to have a capacity of about 200,000 tons per year of ore, yielding about 10,000 tons per year of andalusite product.
It was realized that the larger andalusite crystals encountered during mining could have a value in its own right and Zhang et.al. (1996) published a study on the occurrence and the potential use of these crystals: “The deposit of macrocrystal andalusite of Xixia is a super large deposit with the best quality in China,The andalusite crystals are big and perfect in morphology characterized by para square or rhombic prism,generally 6 9cm in length and 3 5cm in width.The biggest one is up to 30cm in legth or 8cm in width.The colors are light red,brown red,rose red,brown,or greyish white.The hardness is 6.5-7.The transparency is translucent to transparent.The andalusite crystals are used to make ring,button, beads,necklace,wristlet,showing good market perspective”. Unfortunately only the abstract is available on the internet.
“The crystals are used to manufacture polished slices showing the tessellated interiors of the crystals and into balls usually over 3 cm in diameter” <sup>1</sup>. A very low percentage ends as mineral specimens.
The geology of the mine is probably discussed in detailed by Wang Keqin et al (1995): The Geological Characteristics and Genesis of the Sangping Andalusite Deposit in Xixia County, China Non-metallic Mining Industry Herald, 1995-05, but this is not an article that I have access to. The mine lies very near the shear zone between the North and South Qinling Belts, one of the main orogens in East Asia, and the geology in and near the shear zone is very complex.
References:
<sup>1</sup>. Rock Currier
Michal J Potter(1997)Kyanite, U.S.GS, Minerals Information
Zhou Shiquan and Feng Zujie (1999): Mineralogical characteristics and usage of macrocrystal andalusite from Xixia, Henan (abstract), Mineral resources and geology 1999-01
Zhang Zongquin, Zhang Guowei, Fu Guomin, Tang Suohan and Song Biao (1996): Geochronology of metamorphic strata in the Qinling Mountains and its tectonic implications, Science in China(Series D), Vol 39 No 3
Andalusite
France,
Brittany, Morbihan, Pontivy, Sainte Brigitte, Les salles de Rohan
"The matrix is a dark schist from the ordovicium ('schiste d'Angers') that also contains fossils: the trilobite Calymene Tristane, Trinucleus, Orthis.... The andalusite formed under the influence of a granitic intrusion, the granite of Rostrenen (linked to the Hercynian orogenesis).
The rocks are cribbled with andalusite crystals: you can see them in the walls of a nearby abbey, built with the local stone. The andalusite, variety chiastolite, is so abundant and caracteristic that the lords of Rohan, who had their castle there, have 9 crystals of chiastolite in their shield, see: [www.heraldique-europeenne.org]
The Franch use the term 'macle' ('twin') for 'chiastolite.I suppose that was becuase they thought the cross in it to be a result of twinning."1
Lacroix (1893) provides crystal drawings and a more detailed description on the andalusite crystals. He also includes a drawing of a Rohan shield from 1222, thus indicating the significance of the locality already then.
references:
1Erik Vercammen (2013) Mindat Messageboard.
A. Lacroix (1893): Minéralogie de la France et de ses colonies, vol 1
Andalusite
Ireland,
Carlow Co., Seskinnamadra
Andalusite schists occur in a 200 - 300m wide and up to 5km long zone in Tomduff County. The schist is considered a potential source for industrial andalusite. The andalusite is formed in the contact aureole of Caledonian granites intruding Ordovician sediments.
References:
Department of Communications, Marine and Natural Resources(2003): The top 55 deposits, brochure
Matthew Parkes and Claire McAteer(2004): The Geological Heritage of Carlow, Irish Geological Heritage Programme Geological Survey of Ireland
Andalusite
Italy,
Calabria, Reggio Calabria Province, Aspromonte Massif
Andalusite in nodules to 15cm, and as good crystals, occurs in pegmatites of peraluminous granites. 3-4cm crystals are also found in pegmatite erratics from Marro river quartz, schorl, k feldspat and muscovite, this occurrence is described by Carlino, P. (1972)( L'andalusite di S. Giorgio Morgeto (Reggio Calabria). Società Italiana di Mineralogia e Petrografia, Rendiconti, 28, 413-421)
reference:
Ferdinando Giovine (2013), Mindat messageboard
Andalusite
Italy,
Lombardy, Sondrio Province, Bregaglia Valley
Andalusite is fairly widespread in the Bregaglia valley. It occurs as a rock forming mineral in metamorphosed pelittic rocks(mica schists) in the contact aureole ot the Bregaglia granite intrusion late in the Alpine orogeny (30MA). Individual andalusite crystals of a pinkish-salmon-brown colour occurs in quartz veins in the mica scists. It occasionally occurs together with both kyanite and sillimanite being one of the very few places where all these polymorphs occur together.
Generally, the crystals are not well formed, but from the 1980-ties onwards, well formed prisms of pink-brown color and a length of up to about 10 cm has been found in quartz veins in mica schist near Canete. These crystals are most often opaque,but occasionally partly transparent.
References
Kurt Bucher-Nurminen(1977) Die Beziehung zwischen Deformation, Metamorphose und Magmatismus im Gebiet der Bergeller Alpen, Schweizer mineral. petrogr. Mitt. 57, 413-434,
Antonio Costa(2005): Ricordi di Canete, IVMMagazine, Bollettino dell'Istituto di Mineralogia "F. Grazioli" 1/2005
H.-R. Wenk (2012): Geologische Exkursionen im Bergell , Ausstellung in der Ciäsa Granda, Talmuseum in Stampa Gr.
Andalusite
Italy
Tuscany, Elba, Grotta al Guerrino.
“Recently a few beautiful specimens have been collected…with pink, 3 to 4-cm crystals in a granite matrix.”1 Grotta al Guerrino is near the much more famous San Piero in Campo locality that is famous for elbaite. I have never seen any of these but sure would like to.
1 Mineralogical Record, Vol.16, 1985, p356.
Andalusite
Portugal,
Viana do Castelo District, Viana do Castelo, Carreço
The andalusite var chiastolite from Carreço occurs in the Valongo Formation. These are slate and greywacke rocks that has undergone LP–HT contact metamorphism related to the intrusion of the Variscan granitoids. The andalusite has formed in regional geological events and similar occurrences are known from many localities in Northern Portugal and Spain. According to Pamplona et.al (2006), andalusite var chiastolite up to 7cm occurs with garnet, cordierite and scarce sillimanite. Andalusite being the only mineral in this paragenesis that are of interest for mineral collectors, and the up to 14cm long crystals pictured here is obviously larger than average.
References:
Jorge Pamplona, Gabriel Gutierrez-Alonso and Antonio Ribeiro(2006): Superposition of shear zones during orogenic development: an example from the NW Variscan Belt (Viana do Castelo, NW Portugal)Journal of structural geology xx 1-11
Pamplona J.,Dias R. & Ribeiro A.(1993): Tectonic Study of Autochthonous of Viana do Castelo's region - N of Portugal (abstract), Presented in the XII Reunião de Geologia do Oeste Peninsular, Évora, 1993, Terra nova Abstracts, nº 6, vol.5, p.4-5
Andalusite
Russia,
Eastern-Siberian Region, Prebaikalia (Pribaikal'e), Buriatia (Buryatia), Mama River Basin
Andalusite
Russia,
Eastern-Siberian Region, Transbaikalia (Zabaykalye), Buriatia (Buryatia) Republic, Dzhida Basin, Ichetuyskoye (Ichetuiskoe)
Andalusite
Spain,
Andalusia, Córdoba, Hornachuelos, Sierra Albarrana, Cerro de la Sal quarry
The Cerro del Sel quarry lies in an area where metasedimentary and supracrustal volcanic rocks have undergone a high temperature /low pressure metamorphosis. Azor and Ballevre (1997) divides the rocks in zone based on their metamorphic grade and main PT indicator minerals, finding that the zones runs roughly parallel with a shear zone. They conclude that HT fluid flow in the shear zone may have contributed to the metamorphism. Andalusite is formed from metapelites in the “Staurolite-Andalusite” zones, forming crystals up to 5 cm embedded in the fine grained schist. Better crystals up to 10cm can be found in quartz veins penetrating the schists. There is also several pegmatites penetrating the higher grade rocks ( such as the andalusite-staurolite schists), but these do not contain andalusite.
references:
A.Azor, M. Ballevre (1997)Low pressure Metamorphism in the Sierra Alberrana Area (Variscan Basin, Iberian Massif) Journal of Petrology, volume 38, no 1 pp 35-64
.
Maria del Mar Abad-Ortega et.al(1993): The feldspars of the Sierra Albarrana granitic pegmatites, Cordoba, Spain Canadian Mineralogist Vol. 31, pp. 185-242
Andalusite
Spain
Asturias, Boal, Doiras
Boal is considered the best Spanish locality for andalusite var. chiastolite (Galan and Garcia Guinea, 1984) and is one of many chiastolite bearing regions in the northwestern Iberian Peninsula.
Chiastolite ( Lapis crucifer) was used as an amulet by pilgrims on their way to Santiago de Compostela. Chiastolite from the shales near Santiago de Compostela was already known by José Torrubia which in his great work “El Aparato para la Historia Natural Española “ in 1754 describes in detail the occurrence “small Stones in shales (which) is engraved with a black cross in the body of the stone” Boal lies relatively close to the pilgrim route and was probably known already then.
As for all localities that have been known for centuries, it is hard to say how large the largest crystals get, but the up to 5 cm crystals pictured here should give an indication. The chiastolite occurs in ordivician shales folded and metamorphosed to “chlorite facies” by three deformation events in the Variscian orogeny. The chiastolite has formed in a high temperature/low pressure contact aureole around the Boal granite intrusion in a late phase of the Variscian orogeny.
References:
José Torrubia (1754) El Aparato para la Historia Natural Española
GALAN, E and GARCIA GUINEA, J(1984): Precious and semi-precious stones of Spain. Non-metallic Mineral Ores, Volum 15 (24) Proceedings of the 27th international geological congress Moscow 4-14 aug
Florentino Azpeitia Moros(1924): Minerales y mineralogistas españoles
Instituto Geologico y Minero de España (1980) Mapa Geologico de España, BOAL
Andalusite
Spain,
Asturias, Boal, Doiras, Froseira
Andalusite
USA,
California, Imperial Co., Cargo Muchacho Mts, Cargo Muchacho District (Hedges District; Ogilby District), Obregon, American Girl Mine (Cargo Mine; Cargo Muchacho Mine)
The American Girl mine has been mined for gold found as disseminations and in fractures in three distinct veins. The mine has been operated in periods from 1892 to 1962, and a total of 205,000 tons of ore has been mined.
Andalusite is a common mineral at this locality and thousands of crystals have been found, mostly imperfect because of the perfect cleavage and the need to break them from the rock. They are very brittle. The color is generally a opaque dark gray to brown. Rarely stones have been cut from the material, but stone larger than 1 carat are rare. A rough and cut example was donated to the San Bernardino Co. Museum some years ago by Bill Besse who has dug as much as anyone at the locality.
Andalusite is found together with kyanite near the contact between metasedimentary rocks of the jurrassic Tumco formation and later granites. Gases released by the solidifying melt has interacted with the metasedimentary rocks (pneumatolitic action), enriching the schist in Al and Si, thus allowing andalusite and kyanite to form.
Andalusite in similar environments are known from other mines in the vicinity and The Minerals of California gives a locality of Bluebird (Vitrefax) Mine and there is andalusite there, but by far the better locality is the American Girl Mine which is located about a mile east in the American Girl mine. The American Girl mine is a big open pit mine and underground but the andalusites are found in the part of the American Girl mine that is small pit that was worked prior to the development of the large open pit mine. This pit is about midway between the big open pit of the American Girl mine and the Bluebird Mine.
References:
Bill Besse, Personal communication 2003 ( Rock Currier)
Joseph Murdoch, Robert Wallace Webb (1966): Minerals of California, Centennial Volume, Bulletin 189 California Division of Mines and Geology
Walter W. Bradley (1940):, Quarterly Chapter of State Mineralogist Report XXXVI, California Journal of Mines and Geology, Vol 36. No 1
G.Haxel, J.Dillon (1973): The San Andreas Fault System in Southernmost California, Proceedings of the Conference on Tectonic Problems of the San Andreas Fault System
Andalusite
United States
California, Los Angeles County, Beverly Hills.
In crystals in slate up to 15 cm long. These are pretty ugly creatures that only a mother could love, but remember Beverly Hills is right next to Hollywood and that has got to count for something!
Andalusite
USA, California, Mono Co., White Mts, Laws, White Mountain, Champion Mine (White Mountain Mine)
The Champion Mine explores an andalusite rich quartz body that is enclosed in an aluminiferous schistose rock. The schists are a metamorphosed upper Proterozoic through Cambrian sequence of carbonate, quartz sandstone and shale that was deposited in a shallow-marine continental- shelf environment and an Ordovician strata that consists of dark argillite, chert, and shale deposited in a deep-water marine environment. The andalusite bearing quartz body was formed by pneumatolic action on the metasediments by the emplacement of the nearby Birch Creek Pluton.
The andalusite rich quartz mass that is about two miles long and varies from 20 to 70 feet thick. Workings include a 500 ft long adit with stopes up to 100 ft long, 50 ft wide, and 75 ft high; a 400 ft adit and several pits. Between 1920' and 1945, about 26,457 tons averaging about 53 percent andalusite were mined for the Champion Spark Plug Company. There are still large, but uneconomic masses of andalusite left; 2 million tons may remain at the Main workings, and as much as 250,000 tons averaging 40 percent andalusite are about 0.75 mi southwest.
Even today, excellent specimens may be found here. Most of the andalusite mined consisted of a loose mass of intergrown prismatic crystals that may reach several inches in length. While the prism faces are prominent, terminated crystals are less common. The prisms are commonly a blue gray in color but occasional specimens of a light green have been found. The andalusite commonly has a white coating of some claylike mineral but this is just a surface alteration and no completely pseudomorphed specimens have been found.
The andalusite bodies frequently contain small crystals of lazulite in cavities and often small groups of pyrite crystals may be found associated with the lazulite. The best specimens of andalusite came from the early workings and the best specimens come from the large dump below the main Champion Sillimanite Mine, the Vulcanus # 1 Workings. Large bladed crystals associated with pyrophyllite(?) have also been found in the C.P. Stope, a small working above the main mine.
References:
J. F. (Fen) Cooper (2002): Champion Sillimanite Mine, White Mountain Mono County, California, Bay Area Mineralogist Field Trip Guide
Steven W. Schmauch, David A. Lipton, Richard L. Rains, and Richard A. Winters (1983): Summary Report, Mineral Investigation of the White Mountain rare II Area (No. A5058), Inyo and Mono Counties, Califirnia and Esmaralda and Mineral Counties, Nevada, United States Department of the Interior (Bureau of Mines) Open File Report MLA .94-83
Andalusite
USA,
Massachusetts, Worcester Co., Lancaster
Andalusite near Lancaster occurs in pelitic layers in the lower Devonian and Silurian Worcester formation where andalusite porphyroblasts average 3 to 4 cm in length and 0. 5 cm in diameter, but can locally grow as large as 10 cm long and 1.5 cm in diameter, or in the words of Perry and Emerson (1903):
“(The Worcester phyllite) contains large, beautiful crystals of chiastolite clearly marked by distinct crosses appearing in the ends of the crystals. These crystals are frequently an inch in diameter, and several inches in length. Moreover, we may notice in some specimens what were evidently crystals of chiastolite, but which are now simply masses of mica preserving the shape of the chiastolite crystals. This illustrates how one mineral may change into another, while imbedded in the rock, assuming the crystalline form of the new mineral as in the mica scales, yet the whole mass of scales preserves the shape of the original crystal.”
This is a classic American locality for chiastolite, and was probably known already late in the 18h century when rocks from the Worcester formation was quarried for roofing slates and tombstones in Lancaster.
References:
Norman L. Hatch Jr., Editor (1991): The Bedrock Geology of Massachusetts, US Geological Survey Professional paper 1366 E-J
Joseph H. Perry and Benjamin K. Emerson (1903): Geology of Worcester, Massachusetts, Worcester Natural History Society, publication
Andalusite
United States
Pennsylvania, Upper Pridence.
“ two sharply-crystalized, long-prismatic, “andalusite” clusters.”1 These were part of the Joseph Leidy collection (late 19th century) at Swathmore College that Arthur Montgomery rescued from a basement at the college and are now at Lafayette College in Pennsylvania. If Arthur was impressed with them they must be good though there must be only a handful of such specimens still in existence.
1 Mineralogical Record, Vol.1, 1970 p38.
Andalusite
USA,
South Dakota, Pennington Co., Hill City District.
The Hill City area consists predominantly of pelitic rocks which range from phyllites in the northwest to coarse mica schists in the southeast. The metamorphic grades ( staurolite and sillimanite isograds) are roughly parallel to the contact between granite and schist, indicating a metamorphic aureole related to the granite.
Andalusite occurs mainly in the staurolite zone. Andalusite can be found embedded in the mica schist as short prismatic blocky crystals up to about four inches. The crystals are occasionally terminated. The crystals are brown to brownish pink and easily collectable. They are abundant if you want to take the time to collect them. All the crystals are internally cracked but somewhat translucent on their edges. Mica flakes, partly originating from retrograde metamorphism are often incorporated into the surfaces of the crystals giving them a somewhat sparkling look.
References:
James C. Ratte and Russel G. Wayland (1969): Geology of the Hill City Quadrangle Pennington County South Dakota, A Preliminary Report, Contribution to general Geology, Geological Survey Bulletin 1271-B
Chris Korpi, Dana Point, California (2003), personal communication (Rock Currier).
Andalusite
USA,
Virginia, Campbell Co., Alta Vista
Large crystals of andalusite has been found, they were “blocky in habit and up to a half meter in length! Many of the andalusite crystals are kyanite/mica pseudomorphs (paramorphs) but where the crystal faces show cleavage and in glassy pinkish-brown areas, attractive cabochons can be cut.
reference:
D. Allen Penick, Jr.(1992): Gemstones and decorative ornamental stones of Virginia, Virginia Minerals Vol 38 No 3
Click here to view Best Minerals A and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.
Olav Revheim May 2013
Rock Currier
Crystals not pistols.
Edited 38 time(s). Last edit at 05/15/2013 06:47PM by Olav Revheim.
Can you help make this a better article? What good localities have we missed? Can you supply pictures of better specimens than those we show here? Can you give us more and better information about the specimens from these localities? Can you supply better geological or historical information on these localities?
Andalusite
Al2SiO5
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| Andalusite, Itinga, Araçuaí, MG, Brazil 4.5cm | © JSS |
Andalusite is a relatively common mineral most often found in low to medium grade metamorphic rocks. It is polymorph with kyanite and sillimanite. Andalusite often occurs together with one of these minerals, but rarely with both of them. Cordierite, staurolite , micas and garnets are other common associates of andalusite. Andalusite is formed in low pressure/High temperature environments, and the typical environment will be in argillaceous sediments (i.e formed by clays or other fine grained sediment) in a contact aureole around an intrusion, but it is also often formed as a result of regional metamorphosis. It may also occur in other environments, such as quarts veins and dykes, granite pegmatites, as the result of metasomatic or pneumatolitic action ( chemical alteration due to influence from hydrothermal fluids or gases) or even in low pressure granites.
The crystals are normally prismatic with a square cross section, often with poor terminatons and of a pinksh/brownish colour. They can be quite large, crystals up to 50 cm have been reported from several localities, also some not presented in this article. The crystals are normally translucent to opaque, but transparant crystals and river pebbles has been found in Brazil and Sri Lanka. They make beautiful and attractive gems. Faceted stones up 75 to 100 carats from Brazil are known although faceted stones over 20 carats are extremely rare.
A variety of andalusite that also are used to make jewellery, amulets is chiastolite, This variety is named after the greek letter "chi" (χ) due to cross formed inclusions along the C-axis of the crystals. Chiastolite is formed in the early stages of metamorphosis within the andalusite stability area. After the initial formation of anhedral andalusite grains, but the crystals rapidly get a prismatic outline, pushing aside enclosed matter to form the chiastolite pattern. In a more advances metamorphic grade, the andalusite becomes clear of inclusions.
Andalusite will normally have small amounts of Fe3+ replacing Al in the crystal structure, and sometimes also Mn3+. The content of ferric iron is normally low (rarely more than 5wt% Fe2O3 ), whereas the Mn3+ can be significant, or even dominant (Mn3+>Al). Specimens that are Mn3+ dominant, qualifies as a separate mineral species, kanonaite, and a complete solid solution series exists between the two minerals. The intermediate members of the series, Mn-rich andalusite has a green colour and has it's own varietal name, viridine.
Andalusite is often pseudomorphosed to other minerals, due to changes in the metamorphic grade after andalusite crystals have formed. An increase in metamorphic grade will form kyanite or sillimanite pseudomorphs, and even kyanite after chiastolite with the cross pattern intact are known from the Kola peninsula in Russia. Also mica and pyrophyllite pseudomorphs after andalusite is common. Andalusite is however quite resistant to moth chemical and mechanical weathering at ambient conditions, and may concentrate in sediments. In Transvaal in the Republic of South Africa, millions of tons of andalusite pebbles have concentrated in sediments and are mined as a raw material for producing refractory products used in the metallurgical industry, building materials industry, and others due to it's high temperature volume stability, mechanical strength, thermal shock resistance and creep resistance,
The Transvaal andalusite locality may occationally produce crystals up yo 10cm, but it is not yet included in this artcle as there are no photos uploaded to Mindat. With a few exceptions, only localities with photos included in the article. There are undoubtably localities that could have been included in the article, this includes some of th classic German localities, several Russian localities that produce(d?) large well formed crystals, as well as other localities
Andalusite
Australia,
South Australia, Olary Province, Mount Howden
Andalusite of the chiastolite variety was first described from here in 1902, and soon earned a reputation of producing some of the worlds best chiastolite specimens. Older literature even use the name "howdenite" for andalusite from here. Mt; Howden, itself is not that impressive, being more of a small hill than a mountain, lies ten miles north of Bimbowrie, South Australia.
Anderson (1902) gave the first description of the Mount Howden chiastolite: "The crystals are distinguished by large size, they show the characteristic markings very distinctly, and some exhibit features which, so far as I know, have not hitherto been described. According to Mr. Howden, the Bimbowrie mineral occurs either embedded in argillaceous schist, or as rolled pebbles, along with quartz, jasper, aventurine, etc. Towards the surface, where atmospheric influences are at work, the crystals are fairly easy of extraction, and all the more perfect specimens obtained were weathered out. Mr. Howden states that embedded crystals occur with the long axis parallel to the foliation. The crystals are columnar in habit, elongated in the direction of the vertical axis.
Some specimens reach a length of five to six inches, and one, has a diameter of about two inches. None show well defined crystal outlines, the edges being more or less rounded. When complete the crystals taper to either end, the relation of length to breadth being about 4 : 1. They have a brownish crust, and the surface is spangled with flakes of mica. The colour of a cut crystal varies, grey predominating, but some are reddish brown, and some have a pinkish tinge."
The weathered out crystals have all been picked, and today only those frozen in rock remains. Collecting on the Bimbowrie Station (including the Mt Howden locality) is no longer allowed as it has been turned into a National Park.
In geologic terms, this locality belongs to the Alconie Formation (formerly Alconie Pelite, Conor 2000a), which consist of a lower aluminous pelite unit and an upper dark grey, fine-grained, graphitic psammopelite. The basal unit is andalusite-rich and contains large chiastolite porphyroblasts in several outcrops.
Andalusite can also be found in other metapelite formations belonging to the Curnamona and Strathearn Groups, and consequently good localities are still accessible in the area, Dart (2011) highlights the neighbouring property of Kalabity, where good samples can be found on the hill behind the shearing shed and further north along the valley of Calico Creek.
references:
Anderson, C., (1902): On some specimens of Chiastolite from Bimbowrie, South Australia. Records of the Australian Museum 4(7): 298–302
Trevor Dart (ed) (2011): Mineral Profile – Andalusite, kyanite and sillimanite, The Newsletter of The Broken Hill Mineral Club Inc., Volume 12, Issue 1
Conor, C. H. H., (2002):. Geology of the Olary Domain, Curnamona Province, South Australia, Part 1: Geology. PIRSA Report Book 2002/015
Colin H.H. Conor (2000): Definition of major sedimentary and igneous units of the Olary Domain, Curnamona Province. MESA Journal Vol 19
Andalusite
Australia
Western Australia, Yalgoo Shire, Paynes Find
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| Andalusite, Paynes Find 5 cm | © Ralph Bottrill |
Paynes Find is a gold prospect located in a historically important gold region within the Southern Murchison Province of the Archaen Yilgarn block. On a regional scale, the geology of all these mining areas a quite similar and is dominated by granite intrusions and patches of rocks belonging to the Yalgoo-Singleton greenstone belt. The greenstone belt contains both metasedimentary and metavolcanic rocks. Andalusite is found in areas where metapelitic rocks are influenced by heat from the granite intrusions. According to the literature, andalusite is rather common in this remote area. It is hard to say how good the specimens get, as the search for gold easily overshadows the potential for andalusite specimens.
references:
Paynes Find Gold Limited(2011): Stage 2 planned drilling area, ASX Release
Catherine V. Spaggiari, Robert T. Pidgeon, Simon A. Wilde (2007): The Jack Hills greenstone belt, Western Australia Part 2: Lithological relationships and implications for the deposition of ≥4.0 Ga detrital zircons, Precambrian Research vol 155 pp261–286
Andalusite
Austria,
Tyrol, North Tyrol, Sellrain valley, Lüsens valley (Lisens valley; Lüsens alp; Lisens alp)
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| Andalusite, Lüsens valley 7,9cm specimen | © Edwards Minerals |
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| Andalusite, Lüsens valley 40mm FOV | © Elmar Lackner |
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| Andalusite, Lüsens valley 10 cm specimen | © |
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| Andalusite, Lüsens valley
9 cm specimen | © Terry Burtzlaff |
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| Andalusite, Lüsens valley 6 cm specimen | © Rob Lavinsky |
The “andalusite” from Linsen occurs in pegmatite-like quarz and feldspar lenses in what is termed “mineral-rich micaschists” by several authors. These lenses can become multiple meters wide and tens of meters long. Schmidegg(1949) describes one of the main localities near Lisens where “andalusite” occurs as crystals up to and exceeding 20 cm in a 30cm wide border zone in a large quartz lens . The distribution of andalusite is not uniform, and locally the lens was quite rich in “andalusite”crystals. He also mentions multiple other similar lenses in the continuation of the main lens, but that it was impossible to find many of the “andalusite” localities mentioned in older litereature in the area. The earliest reference I have found on Linsens andalusite is von Leonard (1843), but already then it appears that this locality was widely known and specimens distributed to museums around Europe.
Both Schmidegg and Hoinkes et.al (1982) have investigated these crystals closer and found that they often are fully or partly pseudomorphosed to kyanite and pyrophyllite.
The rocks on this locality belongs to the Ötztal-Complex, which are Variscan (390-295 Ma) rocks, metamorphosed to peak conditions (amphibolite/eclogite facies) before the Alpine orogeny. A systematic regional zonation of the AI2Si05 polymorphs, kyanite, sillimanite and andalusite has been observed in metapelites a within the Ötztal-Complex. The Lisens andalusite localities lies in the sillimanite zone and it is believed that the andalusite bearing quartz/feldspar lenses has formed post peak-conditions in the same Variscan event, as is also the kyanite/ pyrophyllite pseudomorphs.
references:
Gustav von Leonard (1843): Handwörterbuch der topographischen Mineralogie, Akademische Verlags-Handlung von J.C.B. Mohr
G.Hoinkes, F. Purtscheller, R. Tessadri (1982): Polymetamorphose im Ostalpin westlich der Tauern Ötztaler Masse, Schneeberger Zug, Brennermesozoikum, Geol. Paläont. Mitt. Innsbruck Band 12, S 95-113
Joachim Schweigl (1995): Neue geochronologische und isotopengeologische Daten zur voralpidischen Entwicklungsgeschichte im Ötztalkristallin (Ostalpen), Jahrbuch der Geologischen Bundesanstalt, Band 138 Heft 1 S. 131–149
Jürgen Konzett, Georg Hoinkes, Peter Tropper (2003): 5th workshop of alpine geological studies, filed trip guide E4, Alpine metamorphism in the Schneeberg Complex and neighboring units (immediate vicinity of Obergurgl), Geol. Paläont. Mitt. Innsbruck Band 26, S 21-45.
Andalusite
Austria
Vorarlberg, Montafon, Gargellen valley, Vergalda, Heimspitze
 | |
| Andalusite, Heimspitze
4,9 cm crystal | © Dan & Diana Weinrich Minerals |
Andalusite is found near the peak of the Heimspitze in a mica schist belonging to the Silvretta crystalline complex. The locality has been known since late in the 19th century. Rompel (1894) describes dark red andalusite crystals covered with tiny flakes of light colored mica. The individual crystals may reach 9 cm, but generally with poor terminations.
References:
J. Rompel (1894): Ein neuer Fundort for Andalusit auf der Heimspitze In Vorarlberg, Tschermaks Mitt., Bd. 14, s 565—568
Otto Reithofer(1937): Über das Vorkommen von Andalusit in Vorarlberg, Verhandlungen der Geologischen Bundesanstalt.s 191-192
Andalusite
Belgium,
Liège Province, Stavelot Massif, Lienne valley, Lierneux, Petit-Sart, Thier del Preu quarry (Thier del Preux; Tiers del Preu)
Thier del Preu is one of the localities for the Mn-rich andalusite, viridine in the Stavelot massif in Belgium. The mineral occurs in Ordovician Mn-rich metasedimentary slates belonging to the "Sm2c" unit (refered to as the "Colanhan" unit by Geukens, other authors use different naming conventions). The Thier del Preu quarry and is one of the few places where this formation is exposed.
The andalusite occurs as green crystalline masses and crystal groups to more than 5cm in brecciated quartz veins ( bréchoïdes). The andalusite occurs with, and is sometimes partly replaced by green pyrophyllite. Andalusite may also be found as small crystals, often sericitized in the slate.
References:
Michel Blondieau (2005): Les gisements minéraux du Salmien dans le Massif de Stavelot
Fernand Geukens (2008): La carte géologique de Bra – Lirerneux
Kanonaite, Andalusite
Belgium,
Luxembourg Province, Stavelot Massif, Vielsalm, Salmchâteau, Le Coreux
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| Kanonaite, Le Coreux 2 cm FOV | © by Sebastian Axt |
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| Kanonaite, Le Coreux 5 mm FOV | © Antonio Borrelli |
Kanonaite is a mineral where Mn3+ is the dominant element in the octaedral 3+ position in the andalusite molecule, thus justifying the approval as a separate mineral species. Andalusite frequently contains some Mn3+ (viridine variety) but rarly in sufficient quantities to qualify as kanonaite.
At Le Coreux, kanonaite occurs as thin discontinuous veins in both quartz veins and in the phyllite host rock. The individual crystals can be up to several mm in size. The crystals in the quartz veins are near end member kanonaite, except that it is sometimes partially decomposed to a mixture of muscovite and Mn-oxides. The “kanonaite” in the phyllite is of variable composition, often zoned from an andalusite (var viridine) core with Mn-dominant kanonaite rims.
As Mn3+ stabilizes the andalusite molecule at lower temperature, it is believed that the crystallization of the kanonaite has taken place after peak metamorphic conditions, which is consistent with its occurrence as rims in the phyllite and near end-member composition in the late forming quartz veins.
The Le Coreux outcrop is located about 1 km north of Salmchateau. It consists of very dark violet and hard Ordovician metapelites (phyllite) belonging to the “Sm2” formation of the Stavelot massif. These rocks which underwent low-grade metamorphism during late Hercynian times. The original pelites were unusually rich in highly oxidized manganese and contain a wealth of manganese minerals. They are particularly enriched within the late quartz veins and have been studied for over a century.
references
Michel Blondieau (2005): Les gisements minéraux du Salmien dans le Massif de Stavelot
Schreyer W., Bernhardt H.-J., Fransolet A.-M. and Armbruster T. (2004): End-member ferrian kanonaite: an andalusite phase with one Al fully replaced by (Mn, Fe)3+ in a quartz vein from the Ardennes mountains, Belgium, and its origin. Contributions to Mineralogy and Petrology, vol 147, pp 276-287.
Andalusite
Brazil
Bahia, Chapada Diamantina, Serra da Mangabeira.
"Here in pockets in the bed rock are concentrated pockets of gravel that are rich in pebbles of cassiterite but sometimes also contain small pebbles of Andalusite, some of it gem grade. The gem rough found here are almost always rounded translucent to transparent pebbles that are strongly pleochroic; yellow brown to yellow green. Rarely stones are found that are an intense green and are given the varietal name of viridine. The color is caused by manganese. These gem gravels will rarely produce a stone of more than a cm in size. Gem pebbles are also reported to have come from near Santa Tereza in Espirito Santo State. The small gem crystal pictured here was simply labeled Bahia but it is probably from the Chapada Diamantina area. This little crystal would easily cost you $500 to $1000 if you are lucky. Chapada Diamantina is a quartzitic highland plateau running north and south and located east of Salvador in central Bahia. This area is known as the Serra da Mangabeira and located near the small towns of Livramento do Brumado and Paramirim which are 66.5 & 130 km respectively north of Brumado."1
The andalusite found in the placers in the Livramento do Brumado and Paramirim area originates from metapelitic rocks belonging to the Contendas-Mirante volcano-sedimentary belt. The Contendas-Mirante volcano-sedimentary belt is a approximately 190 km long and 65 km wide North-South synform. The belt itself is made up of supracrustal formations, metamorphosed in the westem part of the belt in the greenschist facies and progressively changing eastwards to amphibolite facies.
Andalusite is together with cordierite a dominant mineral in the metapelitic (andalusite or mica) schists and the gem varieties are originates from hydrothermal quartz veins within these schists.
The gem andalusite are extracted as water worn pebbles from placers within this belt, and occurs with quartz, kyanite, diaspore, zincian staurolite, cassiterite, gold, bahianite and eskolaite , the metal ores originating from igneous intrusions. White(1974) locates 34 placers worked for cassiterite in the triangle between Rio de Contas, Livramento do Brumado and Paramirim. These placers has been worked since the 1930-ties.
References:
1Rock Currier
Max G. White(1974): Tin resources of Brazil, USGS Open-File Report: 74-333
Moacyr M. Marinho, Pierre Sabate, Johildo Barbosa (1993): The Contendas-Mirante Volcano-sedimentary belt, Boletim IG-USP. Publicação Especial, vol 15:pp37-72
Paul B Moore, Carlos Do Prado Barbosa, Richard Gaines (1978): Bahianite, Sb3A15014(OH)2, a new species, Mineralogical Magazine Vol 4002 pp179-82
Andalusite
Brazil,
Bahia, Vitória da Conquista, Recruta Farm
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| Andalusite, Vitória da Conquista 4,5 cm | © Rob Lavinsky |
The andalusite var viridine from Vitória da Conquista probably originates from a quartz vein in a meta pellitic schist in the Contendas-Mirante Volcano-sedimentary belt.
Andalusite
Brazil,
Espírito Santo
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| Andalusite, Espírito Santo 1,5 cm | © Martins da Pedra |
Andalusite is found in an area some 15km wide and 40km in length near the town of Santa Teresa in the state of Espirito Santo. The gem material is rarely found in crystals with good form and most of the gemmy material is found as water-wornpebbles. The Brazilian stones usually show a very strong flesh-red andolive-green pleochroism, which is especially well brought out when thestones are cut with the table facet nearly at right angles to the verticalaxis of the crystal.
More detailed information should be available in Luiz Carlos Malta Cantarella (2003): Aspectos Geológicos,mineralógicos e gemológicos da Andaluzita de Santa Teresa, estado do Espírito Santa, and P. K. Ruplinger(1983) Topaz and Andalusite Mining in Brazil Journal of gemnology ; vol. 18, no. 7, 1983. I would appreciate if someone could send me a pdf copy.
Reference:
Michael O’Donoghue (ed.)(2006): Gems Their Sources, Descriptions and Identification Sixth Edition
Andalusite
Brazil
Minas Gerais, Cruzeiro Novo (county), Santa Maria.
“Sometimes in gem color and transparency, nice crystals.,”1 . Green or tan transparent crystals, mostly single but sharp and gemmy up to 5 cm were found but most were less than 2 cm. The best of these transparent crystals were from Minas Gerais, and if you want one you will have to be satisfied with a thumbnail size specimen. It could cost you several hundred dollars or more if you can find one.
1 Mineralogical Record, Vol. 2, 1971, p10.
Andalusite
Brazil,
Minas Gerais, Jequitinhonha valley, Itinga
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| Andalusite, Itinga
8,5cm crystal | © Bráulio |
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| Andalusite, Itinga 1,5cm | © |
Andalusite occurs as a common rock forming mineral in metapelitic schists and shales (Salinas shales) several places in the northern parts of Minas Gerais. Small crystal clusters are known from these rocks, but the best crystals are formed in quartz veins in andalusite bearing mica schists, where crystals exceeding 7 cm are known. Some of the smaller crystals may also be transparent.The localities in Minas Gerais are, together with the occurances near Santa Teresa, the richest source of gem andalusite. The gem andalusite are also known from river placers.
The locality information given on some of these specimens are often inaccurate, partly it appears to protect the locality, partly because the retrieval of the specimens has been illegal and partly because the information has been lost somewhere between the finder and the line of mineral traders. Already Heidinger(1844) who investigated a small quantity of gemmy, partly water worn crystals expressed some frustration over the lack of accurate locality information: “ Die…registrirte Localitȁt ist Rio dos Americanos in Minas Novas in der capitanie von Minas Geraes, eine sehr ausgedehnte Localitȁt, da sie eine ganzen Fluss begreift”.
The andalusite from here are sometimes partly replased by pyrophyllite.
References:
W.Heidinger(1844): Ȕber den durchsichtigen Andalusite aus Minas novas Brasilien, Aus den Abhanellungen der k.bȍhm. Gesellschaft der Wissenschaften (V.Folge, Band 3)
Silva, Cassio Roberto da (2011): Avaliação do risco geológico à exposição de elementos químicos à saúde ambiental, na região de Araçuaí-Itinga, Minas Gerais – Brasil. Tese (Doutorado em Geologia) – Universidade Federal do Rio de Janeiro, Instituto de Geociências, Programa de Pós-Graduação em Geologia
Rui L.B.P. Monteiro, Othon H. Leonardos and Jose Marques Correi A-Neves(1990): An Epigenetic origin for the new scheelite and wolframite occurrences in the middle Jequitinhonha valley, Minas Gerais, Brazil, Revista Brasileira de Geociências 20(l-4):68-74
Andalusite
Brazil,
Minas Gerais, Jequitinhonha valley, Itinga, Jenipapo district
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| Andalusite, Jenipapo district
14 cm specimen | © Martins da Pedra |
Andalusite
China,
Henan Province, Nanyang Prefecture, Xixia Co., Sangping Mine (Xixia Mine)
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| Andalusite, Sangping Mine
20mm crystal | © Alexis Monnerot-Dumaine |
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| Andalusite, Sangping Mine
2,5 cm crystal | © 2010, JGW |
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| Andalusite, Sangping Mine
3 cm crystal | © 2002 John H. Betts |
The Henan Xixia Andalusite Mine in Henan Province is a producer of andalusite for industrial purposes. It is believed to have a capacity of about 200,000 tons per year of ore, yielding about 10,000 tons per year of andalusite product.
It was realized that the larger andalusite crystals encountered during mining could have a value in its own right and Zhang et.al. (1996) published a study on the occurrence and the potential use of these crystals: “The deposit of macrocrystal andalusite of Xixia is a super large deposit with the best quality in China,The andalusite crystals are big and perfect in morphology characterized by para square or rhombic prism,generally 6 9cm in length and 3 5cm in width.The biggest one is up to 30cm in legth or 8cm in width.The colors are light red,brown red,rose red,brown,or greyish white.The hardness is 6.5-7.The transparency is translucent to transparent.The andalusite crystals are used to make ring,button, beads,necklace,wristlet,showing good market perspective”. Unfortunately only the abstract is available on the internet.
“The crystals are used to manufacture polished slices showing the tessellated interiors of the crystals and into balls usually over 3 cm in diameter” <sup>1</sup>. A very low percentage ends as mineral specimens.
The geology of the mine is probably discussed in detailed by Wang Keqin et al (1995): The Geological Characteristics and Genesis of the Sangping Andalusite Deposit in Xixia County, China Non-metallic Mining Industry Herald, 1995-05, but this is not an article that I have access to. The mine lies very near the shear zone between the North and South Qinling Belts, one of the main orogens in East Asia, and the geology in and near the shear zone is very complex.
References:
<sup>1</sup>. Rock Currier
Michal J Potter(1997)Kyanite, U.S.GS, Minerals Information
Zhou Shiquan and Feng Zujie (1999): Mineralogical characteristics and usage of macrocrystal andalusite from Xixia, Henan (abstract), Mineral resources and geology 1999-01
Zhang Zongquin, Zhang Guowei, Fu Guomin, Tang Suohan and Song Biao (1996): Geochronology of metamorphic strata in the Qinling Mountains and its tectonic implications, Science in China(Series D), Vol 39 No 3
Andalusite
France,
Brittany, Morbihan, Pontivy, Sainte Brigitte, Les salles de Rohan
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| Andalusite, Les salles de Rohan
3 cm crystal | © Jacques Malassé |
"The matrix is a dark schist from the ordovicium ('schiste d'Angers') that also contains fossils: the trilobite Calymene Tristane, Trinucleus, Orthis.... The andalusite formed under the influence of a granitic intrusion, the granite of Rostrenen (linked to the Hercynian orogenesis).
The rocks are cribbled with andalusite crystals: you can see them in the walls of a nearby abbey, built with the local stone. The andalusite, variety chiastolite, is so abundant and caracteristic that the lords of Rohan, who had their castle there, have 9 crystals of chiastolite in their shield, see: [www.heraldique-europeenne.org]
The Franch use the term 'macle' ('twin') for 'chiastolite.I suppose that was becuase they thought the cross in it to be a result of twinning."1
Lacroix (1893) provides crystal drawings and a more detailed description on the andalusite crystals. He also includes a drawing of a Rohan shield from 1222, thus indicating the significance of the locality already then.
references:
1Erik Vercammen (2013) Mindat Messageboard.
A. Lacroix (1893): Minéralogie de la France et de ses colonies, vol 1
Andalusite
Ireland,
Carlow Co., Seskinnamadra
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| Andalusite, Seskinnamadra
10,6 cm specimen | © Dr Stephen Moreton |
Andalusite schists occur in a 200 - 300m wide and up to 5km long zone in Tomduff County. The schist is considered a potential source for industrial andalusite. The andalusite is formed in the contact aureole of Caledonian granites intruding Ordovician sediments.
References:
Department of Communications, Marine and Natural Resources(2003): The top 55 deposits, brochure
Matthew Parkes and Claire McAteer(2004): The Geological Heritage of Carlow, Irish Geological Heritage Programme Geological Survey of Ireland
Andalusite
Italy,
Calabria, Reggio Calabria Province, Aspromonte Massif
Andalusite in nodules to 15cm, and as good crystals, occurs in pegmatites of peraluminous granites. 3-4cm crystals are also found in pegmatite erratics from Marro river quartz, schorl, k feldspat and muscovite, this occurrence is described by Carlino, P. (1972)( L'andalusite di S. Giorgio Morgeto (Reggio Calabria). Società Italiana di Mineralogia e Petrografia, Rendiconti, 28, 413-421)
reference:
Ferdinando Giovine (2013), Mindat messageboard
Andalusite
Italy,
Lombardy, Sondrio Province, Bregaglia Valley
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| Andalusite, Bregaglia Valley 25,3mm FOV | © Chinellato Matteo |
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| Andalusite, Bregaglia Valley
8 cm specimen | © FRANCO LAZZARI |
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| Andalusite, Bregaglia Valley
1,1 cm crystal | © G.Fraccaro |
Andalusite is fairly widespread in the Bregaglia valley. It occurs as a rock forming mineral in metamorphosed pelittic rocks(mica schists) in the contact aureole ot the Bregaglia granite intrusion late in the Alpine orogeny (30MA). Individual andalusite crystals of a pinkish-salmon-brown colour occurs in quartz veins in the mica scists. It occasionally occurs together with both kyanite and sillimanite being one of the very few places where all these polymorphs occur together.
Generally, the crystals are not well formed, but from the 1980-ties onwards, well formed prisms of pink-brown color and a length of up to about 10 cm has been found in quartz veins in mica schist near Canete. These crystals are most often opaque,but occasionally partly transparent.
References
Kurt Bucher-Nurminen(1977) Die Beziehung zwischen Deformation, Metamorphose und Magmatismus im Gebiet der Bergeller Alpen, Schweizer mineral. petrogr. Mitt. 57, 413-434,
Antonio Costa(2005): Ricordi di Canete, IVMMagazine, Bollettino dell'Istituto di Mineralogia "F. Grazioli" 1/2005
H.-R. Wenk (2012): Geologische Exkursionen im Bergell , Ausstellung in der Ciäsa Granda, Talmuseum in Stampa Gr.
Andalusite
Italy
Tuscany, Elba, Grotta al Guerrino.
“Recently a few beautiful specimens have been collected…with pink, 3 to 4-cm crystals in a granite matrix.”1 Grotta al Guerrino is near the much more famous San Piero in Campo locality that is famous for elbaite. I have never seen any of these but sure would like to.
1 Mineralogical Record, Vol.16, 1985, p356.
Andalusite
Portugal,
Viana do Castelo District, Viana do Castelo, Carreço
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| Andalusite, Carreço 10 mm crystal | © Rui Nunes 2006 |
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| Andalusite, Carreço
14 cm crystal | © Martins da Pedra |
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| Andalusite, Carreço 4,5 cm crystal | © Martins da Pedra |
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| Andalusite, Carreço
13 mm cross-section | © Jorge M. Alves |
The andalusite var chiastolite from Carreço occurs in the Valongo Formation. These are slate and greywacke rocks that has undergone LP–HT contact metamorphism related to the intrusion of the Variscan granitoids. The andalusite has formed in regional geological events and similar occurrences are known from many localities in Northern Portugal and Spain. According to Pamplona et.al (2006), andalusite var chiastolite up to 7cm occurs with garnet, cordierite and scarce sillimanite. Andalusite being the only mineral in this paragenesis that are of interest for mineral collectors, and the up to 14cm long crystals pictured here is obviously larger than average.
References:
Jorge Pamplona, Gabriel Gutierrez-Alonso and Antonio Ribeiro(2006): Superposition of shear zones during orogenic development: an example from the NW Variscan Belt (Viana do Castelo, NW Portugal)Journal of structural geology xx 1-11
Pamplona J.,Dias R. & Ribeiro A.(1993): Tectonic Study of Autochthonous of Viana do Castelo's region - N of Portugal (abstract), Presented in the XII Reunião de Geologia do Oeste Peninsular, Évora, 1993, Terra nova Abstracts, nº 6, vol.5, p.4-5
Andalusite
Russia,
Eastern-Siberian Region, Prebaikalia (Pribaikal'e), Buriatia (Buryatia), Mama River Basin
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| Andalusite, Mama River Basin 3,5 cm crystal | © Leonid Ioffe |
Andalusite
Russia,
Eastern-Siberian Region, Transbaikalia (Zabaykalye), Buriatia (Buryatia) Republic, Dzhida Basin, Ichetuyskoye (Ichetuiskoe)
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| Andalusite, Ichetuyskoye 9 cm crystal | © B.Z. Kantor |
Andalusite
Spain,
Andalusia, Córdoba, Hornachuelos, Sierra Albarrana, Cerro de la Sal quarry
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| Andalusite, Cerro de la Sal quarry
8 cm specimen | © Carlos Pareja |
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| Andalusite, Cerro de la Sal quarry
8,5 cm crystal | © Martins da Pedra |
The Cerro del Sel quarry lies in an area where metasedimentary and supracrustal volcanic rocks have undergone a high temperature /low pressure metamorphosis. Azor and Ballevre (1997) divides the rocks in zone based on their metamorphic grade and main PT indicator minerals, finding that the zones runs roughly parallel with a shear zone. They conclude that HT fluid flow in the shear zone may have contributed to the metamorphism. Andalusite is formed from metapelites in the “Staurolite-Andalusite” zones, forming crystals up to 5 cm embedded in the fine grained schist. Better crystals up to 10cm can be found in quartz veins penetrating the schists. There is also several pegmatites penetrating the higher grade rocks ( such as the andalusite-staurolite schists), but these do not contain andalusite.
references:
A.Azor, M. Ballevre (1997)Low pressure Metamorphism in the Sierra Alberrana Area (Variscan Basin, Iberian Massif) Journal of Petrology, volume 38, no 1 pp 35-64
.
Maria del Mar Abad-Ortega et.al(1993): The feldspars of the Sierra Albarrana granitic pegmatites, Cordoba, Spain Canadian Mineralogist Vol. 31, pp. 185-242
Andalusite
Spain
Asturias, Boal, Doiras
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| Andalusite, Boal 5 cm specimen | © E-Minerales |
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| Andalusite, Boal 3 cm crystal | © E-Minerales |
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| Andalusite, Boal 2 cm crystal | © E-Minerales |
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| Andalusite, Boal 2,5 cm crystal | © Martins da Pedra |
Boal is considered the best Spanish locality for andalusite var. chiastolite (Galan and Garcia Guinea, 1984) and is one of many chiastolite bearing regions in the northwestern Iberian Peninsula.
Chiastolite ( Lapis crucifer) was used as an amulet by pilgrims on their way to Santiago de Compostela. Chiastolite from the shales near Santiago de Compostela was already known by José Torrubia which in his great work “El Aparato para la Historia Natural Española “ in 1754 describes in detail the occurrence “small Stones in shales (which) is engraved with a black cross in the body of the stone” Boal lies relatively close to the pilgrim route and was probably known already then.
As for all localities that have been known for centuries, it is hard to say how large the largest crystals get, but the up to 5 cm crystals pictured here should give an indication. The chiastolite occurs in ordivician shales folded and metamorphosed to “chlorite facies” by three deformation events in the Variscian orogeny. The chiastolite has formed in a high temperature/low pressure contact aureole around the Boal granite intrusion in a late phase of the Variscian orogeny.
References:
José Torrubia (1754) El Aparato para la Historia Natural Española
GALAN, E and GARCIA GUINEA, J(1984): Precious and semi-precious stones of Spain. Non-metallic Mineral Ores, Volum 15 (24) Proceedings of the 27th international geological congress Moscow 4-14 aug
Florentino Azpeitia Moros(1924): Minerales y mineralogistas españoles
Instituto Geologico y Minero de España (1980) Mapa Geologico de España, BOAL
Andalusite
Spain,
Asturias, Boal, Doiras, Froseira
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| Andalusite, Froseira 3,5 cm crystal | © E-Minerales |
Andalusite
USA,
California, Imperial Co., Cargo Muchacho Mts, Cargo Muchacho District (Hedges District; Ogilby District), Obregon, American Girl Mine (Cargo Mine; Cargo Muchacho Mine)
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| Andalusite, American Girl Mine 11 cm specimen | © WWB |
The American Girl mine has been mined for gold found as disseminations and in fractures in three distinct veins. The mine has been operated in periods from 1892 to 1962, and a total of 205,000 tons of ore has been mined.
Andalusite is a common mineral at this locality and thousands of crystals have been found, mostly imperfect because of the perfect cleavage and the need to break them from the rock. They are very brittle. The color is generally a opaque dark gray to brown. Rarely stones have been cut from the material, but stone larger than 1 carat are rare. A rough and cut example was donated to the San Bernardino Co. Museum some years ago by Bill Besse who has dug as much as anyone at the locality.
Andalusite is found together with kyanite near the contact between metasedimentary rocks of the jurrassic Tumco formation and later granites. Gases released by the solidifying melt has interacted with the metasedimentary rocks (pneumatolitic action), enriching the schist in Al and Si, thus allowing andalusite and kyanite to form.
Andalusite in similar environments are known from other mines in the vicinity and The Minerals of California gives a locality of Bluebird (Vitrefax) Mine and there is andalusite there, but by far the better locality is the American Girl Mine which is located about a mile east in the American Girl mine. The American Girl mine is a big open pit mine and underground but the andalusites are found in the part of the American Girl mine that is small pit that was worked prior to the development of the large open pit mine. This pit is about midway between the big open pit of the American Girl mine and the Bluebird Mine.
References:
Bill Besse, Personal communication 2003 ( Rock Currier)
Joseph Murdoch, Robert Wallace Webb (1966): Minerals of California, Centennial Volume, Bulletin 189 California Division of Mines and Geology
Walter W. Bradley (1940):, Quarterly Chapter of State Mineralogist Report XXXVI, California Journal of Mines and Geology, Vol 36. No 1
G.Haxel, J.Dillon (1973): The San Andreas Fault System in Southernmost California, Proceedings of the Conference on Tectonic Problems of the San Andreas Fault System
Andalusite
United States
California, Los Angeles County, Beverly Hills.
In crystals in slate up to 15 cm long. These are pretty ugly creatures that only a mother could love, but remember Beverly Hills is right next to Hollywood and that has got to count for something!
Andalusite
USA, California, Mono Co., White Mts, Laws, White Mountain, Champion Mine (White Mountain Mine)
The Champion Mine explores an andalusite rich quartz body that is enclosed in an aluminiferous schistose rock. The schists are a metamorphosed upper Proterozoic through Cambrian sequence of carbonate, quartz sandstone and shale that was deposited in a shallow-marine continental- shelf environment and an Ordovician strata that consists of dark argillite, chert, and shale deposited in a deep-water marine environment. The andalusite bearing quartz body was formed by pneumatolic action on the metasediments by the emplacement of the nearby Birch Creek Pluton.
The andalusite rich quartz mass that is about two miles long and varies from 20 to 70 feet thick. Workings include a 500 ft long adit with stopes up to 100 ft long, 50 ft wide, and 75 ft high; a 400 ft adit and several pits. Between 1920' and 1945, about 26,457 tons averaging about 53 percent andalusite were mined for the Champion Spark Plug Company. There are still large, but uneconomic masses of andalusite left; 2 million tons may remain at the Main workings, and as much as 250,000 tons averaging 40 percent andalusite are about 0.75 mi southwest.
Even today, excellent specimens may be found here. Most of the andalusite mined consisted of a loose mass of intergrown prismatic crystals that may reach several inches in length. While the prism faces are prominent, terminated crystals are less common. The prisms are commonly a blue gray in color but occasional specimens of a light green have been found. The andalusite commonly has a white coating of some claylike mineral but this is just a surface alteration and no completely pseudomorphed specimens have been found.
The andalusite bodies frequently contain small crystals of lazulite in cavities and often small groups of pyrite crystals may be found associated with the lazulite. The best specimens of andalusite came from the early workings and the best specimens come from the large dump below the main Champion Sillimanite Mine, the Vulcanus # 1 Workings. Large bladed crystals associated with pyrophyllite(?) have also been found in the C.P. Stope, a small working above the main mine.
References:
J. F. (Fen) Cooper (2002): Champion Sillimanite Mine, White Mountain Mono County, California, Bay Area Mineralogist Field Trip Guide
Steven W. Schmauch, David A. Lipton, Richard L. Rains, and Richard A. Winters (1983): Summary Report, Mineral Investigation of the White Mountain rare II Area (No. A5058), Inyo and Mono Counties, Califirnia and Esmaralda and Mineral Counties, Nevada, United States Department of the Interior (Bureau of Mines) Open File Report MLA .94-83
Andalusite
USA,
Massachusetts, Worcester Co., Lancaster
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| Andalusite, Lancaster 6 cm crystal | © 2002 John H. Betts |
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| Andalusite, Lancaster 2,5 cm across | © 2011 Harold Moritz |
Andalusite near Lancaster occurs in pelitic layers in the lower Devonian and Silurian Worcester formation where andalusite porphyroblasts average 3 to 4 cm in length and 0. 5 cm in diameter, but can locally grow as large as 10 cm long and 1.5 cm in diameter, or in the words of Perry and Emerson (1903):
“(The Worcester phyllite) contains large, beautiful crystals of chiastolite clearly marked by distinct crosses appearing in the ends of the crystals. These crystals are frequently an inch in diameter, and several inches in length. Moreover, we may notice in some specimens what were evidently crystals of chiastolite, but which are now simply masses of mica preserving the shape of the chiastolite crystals. This illustrates how one mineral may change into another, while imbedded in the rock, assuming the crystalline form of the new mineral as in the mica scales, yet the whole mass of scales preserves the shape of the original crystal.”
This is a classic American locality for chiastolite, and was probably known already late in the 18h century when rocks from the Worcester formation was quarried for roofing slates and tombstones in Lancaster.
References:
Norman L. Hatch Jr., Editor (1991): The Bedrock Geology of Massachusetts, US Geological Survey Professional paper 1366 E-J
Joseph H. Perry and Benjamin K. Emerson (1903): Geology of Worcester, Massachusetts, Worcester Natural History Society, publication
Andalusite
United States
Pennsylvania, Upper Pridence.
“ two sharply-crystalized, long-prismatic, “andalusite” clusters.”1 These were part of the Joseph Leidy collection (late 19th century) at Swathmore College that Arthur Montgomery rescued from a basement at the college and are now at Lafayette College in Pennsylvania. If Arthur was impressed with them they must be good though there must be only a handful of such specimens still in existence.
1 Mineralogical Record, Vol.1, 1970 p38.
Andalusite
USA,
South Dakota, Pennington Co., Hill City District.
 | |
| Andalusite, Hill City District, crystal 5 cm across | © 2007 Peter Cristofono |
The Hill City area consists predominantly of pelitic rocks which range from phyllites in the northwest to coarse mica schists in the southeast. The metamorphic grades ( staurolite and sillimanite isograds) are roughly parallel to the contact between granite and schist, indicating a metamorphic aureole related to the granite.
Andalusite occurs mainly in the staurolite zone. Andalusite can be found embedded in the mica schist as short prismatic blocky crystals up to about four inches. The crystals are occasionally terminated. The crystals are brown to brownish pink and easily collectable. They are abundant if you want to take the time to collect them. All the crystals are internally cracked but somewhat translucent on their edges. Mica flakes, partly originating from retrograde metamorphism are often incorporated into the surfaces of the crystals giving them a somewhat sparkling look.
References:
James C. Ratte and Russel G. Wayland (1969): Geology of the Hill City Quadrangle Pennington County South Dakota, A Preliminary Report, Contribution to general Geology, Geological Survey Bulletin 1271-B
Chris Korpi, Dana Point, California (2003), personal communication (Rock Currier).
Andalusite
USA,
Virginia, Campbell Co., Alta Vista
Large crystals of andalusite has been found, they were “blocky in habit and up to a half meter in length! Many of the andalusite crystals are kyanite/mica pseudomorphs (paramorphs) but where the crystal faces show cleavage and in glassy pinkish-brown areas, attractive cabochons can be cut.
reference:
D. Allen Penick, Jr.(1992): Gemstones and decorative ornamental stones of Virginia, Virginia Minerals Vol 38 No 3
Click here to view Best Minerals A and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.
Olav Revheim May 2013
Rock Currier
Crystals not pistols.
Edited 38 time(s). Last edit at 05/15/2013 06:47PM by Olav Revheim.
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Erik, Harjo
Thanks.
Olav
Thanks.
Olav
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Locality Updated: Amaicha del Valle District, Tafí del Valle Department, Tucumán, ArgentinaFrom Raúl Jorge Tauber Larry, 21st May 2013 12:27:33