Kosmochlor
Kosmochlor | |
---|---|
General | |
Category | Inosilicate mineral |
Formula (repeating unit) | NaCr3+Si2O67 |
IMA symbol | Kos[1] |
Strunz classification | 9.DA.25 |
Crystal system | Monoclinic |
Crystal class | Prismatic (2/m) (same H-M symbol) |
Space group | C2/c |
Unit cell | a = 9.57, b = 8.71 c = 5.26 Å; β = 107.49°; Z = 4 |
Identification | |
Color | Emerald-green |
Crystal habit | Prismatic crystals and fibrous aggregates |
Twinning | Simple, lamellar on {100} and {001} |
Cleavage | Good on {110} parting on {001} |
Mohs scale hardness | 6 |
Luster | Vitreous |
Streak | Light green |
Diaphaneity | Semitransparent |
Specific gravity | 3.51-3.60 |
Optical properties | Biaxial (-) |
Refractive index | nα = 1.766 nγ = 1.781 |
Birefringence | δ = 0.015 |
Pleochroism | X = yellowish green; Y = blue-green, grass-green; Z = emerald-green |
Dispersion | r > v |
References | [2][3][4] |
Kosmochlor is a rare chromium sodium clinopyroxene with the chemical formula NaCr3+Si2O6.
The name is from German kosmisch, for its occurrence in meteorites, and the Greek chlor, for green.[4] It was first reported in 1897 from the Toluca meteorite, Jiquipilco, Mexico.[2]
It occurs as a major constituent of some jadeitites and as an accessory mineral of some iron meteorites. Associated minerals include cliftonite (graphite), chromian diopside, troilite at Toluca; daubreelite, krinovite, roedderite, high albite, richterite, chromite (Canyon Diablo); and jadeite, chromite and chlorite (Burma).[3]
References
[edit]- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ a b Kosmochlor on Mindat
- ^ a b Kosmochlor in the Handbook of Mineralogy
- ^ a b Kosmochlor on Webmin