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Formula: K2Cu5O(SO4)5
Sulphate
Crystal System: Triclinic
Specific gravity: 3.41 calculated
Colour: Light green to green
Environments
Cryptochalcite is a relatively new mineral, approved in 2015.
Localities
At the type locality, the Arsenatnaya fumarole, Second scoria cone, Northern Breakthrough, Great Fissure eruption,
Tolbachik Volcanic field, Milkovsky District, Kamchatka Krai, Russia, two new minerals, cryptochalcite and
cesiodymite were found in fumarole sublimates. They are associated with
one another and with euchlorine,
chalcocyanite,
alumoklyuchevskite,
anglesite, fedotovite,
wulffite, langbeinite,
aphthitalite, steklite and
hematite.
Cryptochalcite and cesiodymite are visually indistinguishable
from one another, and form coarse tabular or prismatic crystals or grains up to 0.3 mm in size. They are brittle,
transparent and light green to green, with a vitreous lustre
(EJM 30.593-607).
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