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Formula: Ca4MgB4O6(CO3)2(OH)6
Compound borate
Crystal System: Monoclinic
Specific gravity: 2.77 measured, 2.765 calculated
Hardness: 4
Streak: White
Colour: Greenish-blue to bluish green, nearly colourless
Environments
Metamorphic environments
Hydrothermal environments
Localities
At the Fuka mine, Fuka, Bitchū, Takahashi City, Okayama Prefecture, Japan, borcarite is a rare
secondary mineral probably formed by reaction of late
hydrothermal fluids with brucite. Associated minerals include
olshanskyite,
bultfonteinite, takedaite
and calcite
(HOM).
At the Type Locality, the Snezhnoe B ore occurrence, Izvestkovyi Stream, Titovskoe B deposit, Tas-Khayakhtakh Range,
Dogdo River Basin, Polar Yakutia, Sakha Republic, Russia, borcarite occurs in
kotoite marble, formed in
dolostone near the contact with
granodiorite. The borcarite forms dense masses up to 0.5 m
in diameter and as veins in kotoite
marble and in
ludwigite-szaibélyite-magnetite
rock. It contains inclusions of szaibélyite,
calcite, serpentine,
magnetite and spinel
(AM 50.2097). Other associated minerals include uralborite,
sibirskite and kotoite
(HOM).
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