What is Kosmochlor?
Kosmochlor is a chromium-rich sodium pyroxene with intense green colour, best known from meteorites and unusual chromium-bearing terrestrial rocks.
Mineralogy and crystal structure
Reference formula: NaCrSi2O6. Kosmochlor has a monoclinic clinopyroxene structure and is the chromium analogue of jadeite. Its name reflects its early recognition in meteorites, while terrestrial material can form through chromium-rich metasomatism. Kosmochlor is classified with silicates and has a monoclinic crystal system. Typical hardness is 5.5–6 on the Mohs scale and specific gravity is approximately 3.4–3.6.
Colour, lustre and habit
Typical colours include emerald-green, dark green, black. The usual prismatic, granular, massive habit and vitreous, sub-metallic lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Kosmochlor forms in or is associated with chromium-rich meteorites, chromitites and metasomatic ultramafic environments. Important documented localities include meteorite occurrences, Russia, South Africa, the United States and other chromium-rich localities.
An emerald pyroxene with a planetary connection
Kosmochlor is a standout for collectors who want a mineral that bridges Earth and space. Its saturated green colour is attractive on its own, but the meteorite connection gives even a small specimen an unusual narrative reach.
Collecting and care
Protect crystal faces and retain analytical provenance; do not assume a green pyroxene is kosmochlor without chromium data.
