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Augite
Current inventory:  0 gems
 

Augite

  
Augite was named by Abraham G. Werner in 1792 from the Greek "auge" for "shine" or "luster," in allusion to the appearance of its cleavage surfaces.

Discovered in 1792; IMA status: Valid (pre-IMA; Grandfathered)

 

Chemistry

 

 

Chemical Formula:

(Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6

 

Calcium Sodium Magnesium Iron Aluminum Titanium Silicate

Molecular Weight:

236.35 gm

Composition:

Sodium

0.97 %

Na

1.31 %

Na2O

 

Calcium

15.26 %

Ca

21.35 %

CaO

 

Magnesium

9.26 %

Mg

15.35 %

MgO

 

Titanium

2.03 %

Ti

3.38 %

TiO2

 

Aluminum

4.57 %

Al

8.63 %

Al2O3

 

Iron

4.73 %

Fe

6.08 %

FeO

 

Silicon

22.58 %

Si

48.30 %

SiO2

 

Oxygen

40.62 %

O

 

 

 

 

100.00 %

 

104.40 %

= TOTAL OXIDE

 

 

Classification

   

   

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/F.01-90

Nickel-Strunz 10th Ed. ID:

9.DA.15

 

9 : SILICATES (Germanates)
D : Inosilicates
A : Inosilicates with 2-periodic single chains, Si
2O6; pyroxene family

Related to:

Pyroxene Group. Clinopyroxene Subgroup.

Members of Group:

Pyroxene Group: Canaanite, Clinopyroxene Subgroup, Orthopyroxene Subgroup

Members of Subgroup:

Clinopyroxene Subgroup: Aegirine, Augite, Clinoenstatite, Clinoferrosilite, Diopside, Essenite, Grossmanite, Hedenbergite, Jadeite, Jervisite, Johannsenite, Kanoite, Kosmochlor, Kushiroite, Namansilite, Natalyite, Petedunnite, Pigeonite, Spodumene

Varieties:

Asteroite, Fassaite, Jeffersonite, Korea-Augite, Soda-Augite, Titanian Augite

Synonyms:

Basaltine, Hedenbergite-Ågirin, Violatite, Volcanic Shorl, Volcanite (of Delamétherie)

 

 

Crystal Data

   

   

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Stubby prismatic crystals, square or octagonal in section, to 10 cm; elongated || [001], acicular, skeletal, dendritic. Exsolution lamellae and overgrowths common.

Twinning:

Simple or multiple on {100}, common; also on {001}.

 

 

Physical Properties

   

 

Cleavage:

Good on {110}, (110) ^ (110) ~87°; partings on {100} and {010}

Fracture:

Irregular/Uneven to Conchoidal

Tenacity:

Brittle

Moh's Hardness:

5.5 - 6.0

Density:

3.19 - 3.56 (g/cm3)

Luminescence:

Not Fluorescent

Radioactivity:

Not Radioactive

 

 

Optical Properties

   

   

Color:

Black, brown, greenish, violet-brown; in thin section, colorless to gray; clear cores zoned to dark rims common, also oscillatory and sector zoning.

Transparency:

Transparent to Translucent

Luster:

Vitreous, resinous to dull

Refractive Index:

1.575 - 1.584  Biaxial ( + ) 

Birefringence:

0.009

Dispersion:

Weak to moderate; r > v

Pleochroism:

X = pale green, pale brown, green, greenish yellow; Y = pale brown, pale yellow-green, violet; Z = pale green, grayish green, violet

 

 

Occurances

   

   

Geological Setting:

Essential in mafic igneous rocks, basalt, gabbro; common in ultramafic rocks; in some high-grade metamorphic rocks and metamorphosed iron formations.

Common Associations:

Orthoclase, Sanidine, Labradorite, Olivine, Leucite, amphiboles, pyroxenes

Common Impurities:

Ti, Cr, Na, Mn, K

Type Locality:

Unknown

Year Discovered:

1792

View mineral photos:

Augite Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 


Augite was named by Abraham G. Werner in 1792 from the Greek "auge" for "shine" or "luster," in allusion to the relatively high luster of its cleavage surfaces. Augite is an important rock-forming mineral in many igneous rocks, especially in gabbros and basalts, and is also found in some hydrothermal metamorphic rocks. Augite is a member of the Pyroxene Group and Clinopyroxene Subgroup that includes Aegirine, Augite, Diopside, Hedenbergite, Jadeite, Johannsenite and Spodumene. Augite is found in colors of black, greenish black, brown and violet-brown. It is a relatively rare gem and is mostly for collectors of the unusual.

Distribution: Widespread; only a few classic localities, much studied or providing fine examples, are listed. From Arendal, Norway. In Italy, from Vesuvius, Campania; around Frascati, Alban Hills, Lazio; on Mt. Monzoni, Val di Fassa, Trentino-Alto Adige; at Traversella, Piedmont; and on Mt. Etna, Sicily. Around the Laacher See, Eifel district, Germany. At Ústí nad Lábem (Aussig), Bílina, and Vlcí Hora, near Cernosín, Czech Republic. On the Azores and Cape Verde Islands. In Canada, from Renfrew and Haliburton Counties, Ontario; at Otter Lake, Pontiac County, Quebec; and many other localities. In the USA, from Franklin and Sterling Hill, Ogdensburg, Sussex County, New Jersey; and at Diana, Lewis County, and Fine, St. Lawrence County, New York. From Tomik, Gilgit district, Pakistan. At Kangan, Andhra Pradesh, India.
 

  
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