Science Fair Project Encyclopedia
Augite
| Augite | |
|---|---|
| General | |
| Category | Mineral |
| Chemical formula | (Ca, Mg, Fe, Ti, Al)(Al, Si)2O6 |
| Identification | |
| Colour | Pale brown to purplish or greenish brown |
| Crystal system | Monoclinic |
| Cleavage | {110} good |
| Fracture | uneven |
| Mohs Scale hardness | 5 to 6.5 |
| Luster | Vitreous |
| Refractive index | α = 1.671 - 1.735, β = 1.672 - 1.741, γ = 1.703 - 1.774 |
| Specific gravity | 3.19 - 3.56 |
| Data from Deer et al. (1992). | |
Augite is a mafic mineral described chemically as (Ca, Na)(Mg, Fe, Al)(Al, Si)2O6 or calcium sodium magnesium iron aluminium silicate. Structurally, it is a solid solution of the pyroxene group which also contains diopside and hedenbergite . The crystals are monoclinic and prismatic. It is found in igneous rocks such as gabbros and basalts, and in metamorphic rocks from hydrothermal vents. Occasional specimens have a shiny appearance that give rise to the mineral's name, which is from the Greek augites, meaning "brightness", although ordinary specimens have a dull (dark green, brown or black) finish.
References
- Deer, W. A., Howie, R. A., and Zussman, J. (1992). An introduction to the rock-forming minerals (2nd ed.). Harlow: Longman ISBN 0-582-30094-0
10-26-2009 08:16:03
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The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details