Augite
| Augite | ||
|---|---|---|
Specific gravity 3.19–3.56 | | |
| Optical properties | Biaxial (+) | |
| Refractive index | nα = 1.680–1.735, nβ = 1.684–1.741, nγ = 1.706–1.774 | |
| Birefringence | δ = 0.026–0.039 | |
| Pleochroism | X = pale green, pale brown, green, greenish yellow; Y = pale brown, pale yellow-green, violet; Z = pale green, grayish green, violet | |
| References | [2][3][4] | |
Augite, also known as Augurite, is a common rock-forming
prismatic
. Augite has two prominent cleavages, meeting at angles near 90 degrees.
Characteristics
Augite is a
orthopyroxene: when occurring with either of these other pyroxenes, the calcium content of augite is a function of temperature and pressure, but mostly of temperature, and so can be useful in reconstructing temperature histories of rocks. With declining temperature, augite may exsolve lamellae of pigeonite and/or orthopyroxene. There is also a miscibility gap between augite and omphacite, but this gap occurs at higher temperatures. There are no industrial or economic uses for this mineral.[5][6]
Locations
Augite is an essential mineral in
ultramafic rocks. It also occurs in relatively high-temperature metamorphic rocks such as mafic granulite and metamorphosed iron formations. It commonly occurs in association with orthoclase, sanidine, labradorite, olivine, leucite, amphiboles and other pyroxenes.[2]
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) luster. It was named by Abraham Gottlob Werner in 1792.[3]
See also
References
- S2CID 235729616.
- ^ a b Handbook of Mineralogy
- ^ a b Augite on Mindat.org
- ^ Webmineral data for Augite
- ISBN 047157452X.
- ISBN 9780195106916.
Further reading
Wikimedia Commons has media related to Augite.
- Deer, W. A., Howie, R. A., and Zussman, J. (1992). ISBN 0-582-30094-0
