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Silicate

Chromio-pargasite

NaCa₂(Mg₄Cr)(Si₆Al₂)O₂₂(OH)₂
Hardness6
Crystal systemMonoclinic
ClassSilicate
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Chromio-pargasite specimen

Chromio-pargasite (a.k.a. Ehimeite) exhibited at the Mining Museum of Akita University — Photo: 掬茶 · CC BY-SA 4.0

Chromio-pargasite

Chromio-pargasite is an IMA-recognized mineral species in the silicate class, with the chemical formula NaCa₂(Mg₄Cr)(Si₆Al₂)O₂₂(OH)₂.

It crystallizes in the monoclinic crystal system (space group C2/m). It is a member of the Amphibole structural group.

Key properties: Mohs hardness 6; specific gravity 3.08; Pale green streak; Vitreous luster; optically biaxial.

IMA symbol Cprg, IMA status: approved, named in 2011.

Along cracks in podiform chromitite deposits scattered in serpentinized dunite in association with rocks of the eclogite metamorphic facies; probably developed during retrograde metamorphism.

It is found associated with Chromite, kämmererite, Cr-poor clinochlore, phlogopite, diopside, calcite, uvarovite.

Originally ehimeite for the type locality; subsequently changed to chromio-pargasite to conform to IMA nomenclature for a chromium-dominant analog of pargasite.

Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet. Browse more C minerals or help write this entry.