Chemistry:Kosmochlor

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Kosmochlor
Kosmochlor jade, Jurassic, Burma 1.jpg
Chromite (metallic black), kosmochlor pyroxene (emerald green to dark green to black), chromian jadeite pyroxene (green), chromiferous arfvedsonite amphibole (green or gray), symplectite (green, a finely-crystalline mineral mix of mostly chromian jadeite)
General
CategoryInosilicate mineral
Formula
(repeating unit)
NaCr3+Si2O67
Strunz classification9.DA.25
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupC2/c
Unit cella = 9.57, b = 8.71
c = 5.26 Å; β = 107.49°; Z = 4
Identification
ColorEmerald-green
Crystal habitPrismatic crystals and fibrous aggregates
TwinningSimple, lamellar on {100} and {001}
CleavageGood on {110} parting on {001}
Mohs scale hardness6
|re|er}}Vitreous
StreakLight green
DiaphaneitySemitransparent
Specific gravity3.51-3.60
Optical propertiesBiaxial (-)
Refractive indexnα = 1.766 nγ = 1.781
Birefringenceδ = 0.015
PleochroismX = yellowish green; Y = blue-green, grass-green; Z = emerald-green
Dispersionr > v
References[1][2][3]

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.[3] It was first reported in 1897 from the Toluca meteorite, Jiquipilco, Mexico.[1]

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).[2]

References

  1. 1.0 1.1 Kosmochlor on Mindat
  2. 2.0 2.1 Kosmochlor in the Handbook of Mineralogy
  3. 3.0 3.1 Kosmochlor on Webmin
  4. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine 85 (3): 291–320. doi:10.1180/mgm.2021.43. Bibcode2021MinM...85..291W.