Help mindat.org|Log In|Register|
Home PageMindat NewsThe Mindat ManualHistory of MindatCopyright StatusManagement TeamContact UsAdvertise on Mindat
Donate to MindatSponsor a PageSponsored PagesTop Available PagesMindat AdvertisersAdvertise on MindatThe Mindat Store
Minerals by PropertiesMinerals by ChemistryRandom MineralSearch by minIDLocalities Near MeSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
Keyword(s):
 
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportAdd Glossary Item
StatisticsMember ListBooks & MagazinesMineral Shows & EventsThe Mindat DirectoryHow to Link to MindatDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day Gallery

Augite

This page is currently not sponsored. Click here to sponsor this page.
Augite-Diopside-hedenbergite Quadrilateral
Formula:
(Ca,Na)(Mg,Fe2+,Al,Fe3+,Ti)[(Si,Al)2O6]
System:
Monoclinic
Colour:
Brown-green, black, ...
Lustre:
Vitreous, Resinous, Dull
Hardness:
5½ - 6
Name:
Named by Abraham G. Werner in 1792 from the Greek αυγή ("auge") for "shine" or "luster," in allusion to the appearance of its cleavage surfaces. The modern definition of augite is that it is relatively low in calcium with some disorder of occupancies of Fe2+ and Mg in both octahedral sites. Fe:Mg may vary from 0 to 1 by definition. Augites tend to have minor (up to 10 atomic percent) Na, Al, Ti, or Fe3+ substitution that also may be disordered in the M2 and M1 sites. The full Ca, ordered equivalent of augite is the diopside-hedenbergite series.
Pyroxene Group, Clinopyroxene Subgroup. In the Ca-Fe-Mg (diopside-hedenbergite-augite) quadrilateral, the ideal structural formula is M2M1[Si2O6], where M2 is a distorted octahedral site which preferentially accepts large cations such as alkaline earth/alkali atoms (Ca, but may accept transition metals) and where M1 is a smaller regular octahedral site preferentially accepting transition metals, etc. (most commonly Mg, Fe2+). The substitutions containing no changes in valence within M2 (2+), Mi (2+), and tetrahedral sites, T (4+), is the normal scheme. A variety of additional substitution schemes, which require coupling of substituents, have been identified in these pyroxenes. Often these substitutions result in a change of species designation when they are dominant. Substitution 1 has Na substitution in M2 and trivalent ions of Al, Fe, Cr, and Sc substituting in M1. Substitution 2 involves Na substitution in M2 and mixed valance transition metals such as [Fe2+0.5Ti4+0.5] substituting in M1. Substitution 3, also called Tschermak's Component, involves coupled M1 octahedral and tetrahedral substitutions, such as CaAl[AlSiO6] or CaTi3+[AlSiO6]. Substitution 4 is a variant of Substitution 2 and has dominant Ca in M2 with mixed valence substitution in M1 involving divalent and tetravalent Ti and Al substitution in tetrahedral sites (e.g. Ca[(Mg, Fe2+)0.5Ti4+0.5)][AlSiO6]. In highly substituted Ca-Fe-Mg pyroxenes, several substitutional schemes may be identified. Substitution schemes 2 and 4 have not yet yielded named mineral species.

Augite is not just a member of the diopside-hedenbergite series. Augite is generally, sub-calcic, compared with diopside-hedenbergite. Augite, as defined by Morimoto, et al. (1988) may have Fe>Mg or Mg>Fe without change in name. Because of the unique way augite has been defined (Morimoto, et al, 1988), there is the implication that in rare cases, a variety of anions may be dominant in various the various sites, including M2, M1, and T. These extreme compositions are rare in the large majority of augites. The augites with En80Fo20 or Fs80Fo20 could be thought of as slightly alkalic clinoenstatite-clinoferrosilite. However, detailed chemical analysis and even structural analysis should be obtained in order to properly classify these unusual compositions. Similarly, extensive substitution of Na, for example, as in scheme 1 (Morimoto, et al., 1988) could lead to aegirine-augite or aegirine compositions depending on the other elements involved.


Visit gemdat.org for gemological information about Augite.

Classification of Augite

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
9.DA.15

9 : SILICATES (Germanates)
D : Inosilicates
A : Inosilicates with 2-periodic single chains, Si2O6; pyroxene family
65.1.3a.3

65 : INOSILICATES Single-Width,Unbranched Chains,(W=1)
1 : Single-Width Unbranched Chains, W=1 with chains P=2
16.23.1

16 : Silicates Containing Aluminum and other Metals
23 : Aluminosilicates of Fe, Ca, and Mg
mindat.org URL:
http://www.mindat.org/min-419.html
Please feel free to link to this page.

Occurrences of Augite

Geological Setting:
Major rock forming mineral in mafic igneous rocks, ultramafic rocks and some high grade metamorphic rocks.

Physical Properties of Augite

Vitreous, Resinous, Dull
Diaphaneity (Transparency):
Translucent, Opaque
Colour:
Brown-green, black, green-black, brown, purplish brown
Streak:
Greenish gray, light to dark brown
Hardness (Mohs):
5½ - 6
Tenacity:
Brittle
Cleavage:
Distinct/Good
Good on {110}
Parting:
on {100} and {010}
Fracture:
Irregular/Uneven, Sub-Conchoidal
Density:
3.19 - 3.56 g/cm3 (Measured)    3.31 g/cm3 (Calculated)

Crystallography of Augite

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/b
Space Group Setting:
C2/c
Cell Parameters:
a = 9.699Å, b = 8.844Å, c = 5.272Å
β = 106.97°
Ratio:
a:b:c = 1.097 : 1 : 0.596
Unit Cell Volume:
V 432.53 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Stubby prismatic crystals
Twinning:
Simple or multiple on {100}, also on {001}
Comment:
Axial setting is C1 2/c 1

Crystallographic forms of Augite

Crystal Atlas:
Image Loading
Click on an icon to view
Augite no.24 - Goldschmidt (1913-1926)
Augite no.111 - Goldschmidt (1913-1926)
3d models and HTML5 code kindly provided by www.smorf.nl.

Toggle
Edge Lines | Miller Indicies | Axes

Transparency
Opaque | Translucent | Transparent

View
Along a-axis | Along b-axis | Along c-axis | Start rotation | Stop rotation
X-Ray Powder Diffraction Data:
d-spacingIntensity
3.22 (70)
2.99 (100)
2.94 (60)
2.90 (30)
2.56 (40)
2.53 (30)
2.51 (50)
2.13 (30)
Comments:
ICDD 41-1483 (titanian augite)

Optical Data of Augite

Type:
Biaxial (+)
RI values:
nα = 1.680 - 1.735 nβ = 1.684 - 1.741 nγ = 1.706 - 1.774
2V:
Measured: 40° to 52°, Calculated: 48° to 68°
Birefringence:
0.032
Max Birefringence:
δ = 0.026 - 0.039
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
High
Dispersion:
r > v weak to distinct
Optical Extinction:
Z : c = 35°-48°
Pleochroism:
Visible
Comments:
X= pale green, pale brown, green, greenish yellow
Y= pale brown, pale yellow-green, violet
Z= pale green, grayish green, violet

Chemical Properties of Augite

Formula:
(Ca,Na)(Mg,Fe2+,Al,Fe3+,Ti)[(Si,Al)2O6]
Essential elements:
All elements listed in formula:
Common Impurities:
Ti,Cr,Na,Mn,K

Relationship of Augite to other Species

Other Members of Group:
AegirineNaFe3+Si2O6
Aegirine-augite(Na,Ca)(Fe3+,Fe2+,Mg,Al)Si2O6
ClinoenstatiteMgSiO3
ClinoferrosiliteFe2+SiO3
DiopsideCaMgSi2O6
EsseneiteCaFe3+[AlSiO6]
GrossmaniteCaTi3+ AlSiO6
HedenbergiteCaFe2+Si2O6
JadeiteNa(Al,Fe3+)Si2O6
Jervisite(Na,Ca,Fe2+)(Sc,Mg,Fe2+)Si2O6
JohannseniteCaMn2+Si2O6
KanoiteMn2+(Mg,Mn2+)Si2O6
KosmochlorNaCrSi2O6
KushiroiteCaAl[AlSiO6]
NamansiliteNaMn3+Si2O6
NatalyiteNa(V3+,Cr)Si2O6
Omphacite(Ca,Na)(Mg,Al)Si2O6
PetedunniteCa(Zn,Mn2+,Mg,Fe2+)Si2O6
Pigeonite(Mg,Fe2+,Ca)(Mg,Fe2+)Si2O6
SpodumeneLiAlSi2O6
9.DA.05Donpeacorite(Mn2+,Mg)Mg[SiO3]2
9.DA.05EnstatiteMgSiO3
9.DA.05FerrosiliteFeSiO3
9.DA.10ClinoenstatiteMgSiO3
9.DA.10ClinoferrosiliteFe2+SiO3
9.DA.10KanoiteMn2+(Mg,Mn2+)Si2O6
9.DA.10Pigeonite(Mg,Fe2+,Ca)(Mg,Fe2+)Si2O6
9.DA.15DiopsideCaMgSi2O6
9.DA.15EsseneiteCaFe3+[AlSiO6]
9.DA.15HedenbergiteCaFe2+Si2O6
9.DA.15JohannseniteCaMn2+Si2O6
9.DA.15PetedunniteCa(Zn,Mn2+,Mg,Fe2+)Si2O6
9.DA.15DavisiteCaScAlSiO6
9.DA.15KushiroiteCaAl[AlSiO6]
9.DA.15GrossmaniteCaTi3+ AlSiO6
9.DA.20Aegirine-augite(Na,Ca)(Fe3+,Fe2+,Mg,Al)Si2O6
9.DA.20Omphacite(Ca,Na)(Mg,Al)Si2O6
9.DA.25AegirineNaFe3+Si2O6
9.DA.25JadeiteNa(Al,Fe3+)Si2O6
9.DA.25Jervisite(Na,Ca,Fe2+)(Sc,Mg,Fe2+)Si2O6
9.DA.25KosmochlorNaCrSi2O6
9.DA.25NamansiliteNaMn3+Si2O6
9.DA.25NatalyiteNa(V3+,Cr)Si2O6
9.DA.30SpodumeneLiAlSi2O6
16.23.2DorriteCa4(Mg3Fe93+)O4(Si3Al8Fe3+O36)
16.23.3Vesuvianite(Ca,Na,☐)19(Al,Mg,Fe3+)13(☐,B,Al,Fe3+)5(Si2O7)4(SiO4)10(OH,F,O)10
16.23.5Ferro-hornblende☐{Ca2}{Fe42+Al}(AlSi7O22)(OH)2
16.23.6Magnesio-hornblende☐{Ca2}{Mg4Al}(AlSi7O22)(OH)2
16.23.7Aerinite(Ca5.1Na0.5)(Fe3+,Al,Fe2+,Mg)4(Al,Mg)6[HSi12O36(OH)12][(CO3)1.2(H2O)12]

Other Names for Augite

Name in Other Languages:
Basque:Augita
Catalan:Augita
Croatian:Augit
Czech:Augit
Dutch:Augiet
Esperanto:Aŭgito
Finnish:Augiitti
French:Augite
Hebrew:אוגיט
Hungarian:Augit
Italian:Augite
Japanese:普通輝石
Lithuanian:Augitas
Polish:Augit
Russian:Авгит
Serbian (Cyrillic Script):Аугит
Simplified Chinese:普通辉石
Swedish:Augit
Tajik (Cyrillic Script):Авгит
Ukrainian:Авгіт

Other Information

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Augite

Reference List:
Dana, E. S. (1892) Dana's Systerm of Mineralogy, 6th edition, New York, NY: 352-364.
Clark, J.R., D.E. Appleman, and J.J. Papike (1969) Crystal-chemical characterization of clinopyroxenes based on eight new structure refinements. MSA Special Paper 2: 31-50.
Robinson, P., Ross, M., Nord, G.L., Smyth, J.R., and Jaffe, H.W. (1977) Exsolution lamellae in augite and pigeonite: fossil indicators of lattice parameters at high temperature and pressure. American Mineralogist: 62: 857-873.
Phillips, W. R. and D. T. Griffin (1981) Optical Mineralogy: 196-198.
Morimoto, N., Fabries, J., Ferguson, A. K., Ginzburg, I. V., Ross, M., Seifert, F. A., Zussman, J., Aoki, K., and Gottardi, G. (1988) Nomenclature of Pyroxenes, American mineralogist, v. 73, p. 1123-1133.
Deer, Howie, and Zussmann (1997): 2A: 294-398.

Internet Links for Augite

Specimens:
The following Augite specimens are currently listed for sale on minfind.com.

Localities for Augite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Mineral and/or Locality  
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2015, except where stated. Mindat.org relies on the contributions of thousands of members and supporters.
Privacy Policy - Terms & Conditions - Contact Us Current server date and time: September 2, 2015 01:23:38 Page generated: September 1, 2015 18:31:33