Oxy-chromium-dravite

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Formula: NaCr₃(Cr₄Mg₂)(Si₆O₁₈)(BO₃)₃(OH)₃O
Cyclosilicate, tourmaline group, chromium- and boron- bearing mineral
Crystal System: Trigonal
Specific gravity: 3.299 calculated
Hardness: 7½
Streak: Green
Colour: Emerald-green
Environments

Metamorphic environments

Oxy-chromium-dravite is a relatively new mineral, approved in 2012.

Localities

At the type locality, the Pereval marble quarry, Slyudyanka, Lake Baikal area, Irkutsk Oblast, Russia, oxy-chromium-dravite has been found in association with quartz, calcite, chromphyllite, eskolaite, chromite, uvarovite, chromium-bearing phlogopite, diopside-kosmochlor, chromium-bearing tremolite, chromium-bearing titanite, chromium-bearing rutile, and pyrite, in quartzite, and with chromium/vanadium-bearing diopside, quartz, calcite, magnesiochromite, eskolaite-karelianite in quartz-diopside rock. Crystals are emerald green and transparent, with a vitreous lustre and a green streak. The occurrence is in chromium/vanadium-bearing calcite - quartz - diopside metamorphic rocks of the granulite facies (AM 97.11.2024-2030, HOM).

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