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Formula: Ca3B2O6
Anhydrous borate
Crystal System: Trigonal
Specific gravity: 3.10 measured, 3.12 calculated
Hardness: 4½
Streak: White
Colour: White, pale grey, colourless
Solubility: Easily soluble in dilute hydrochloric acid
Environments
Metamorphic environments
Hydrothermal environments
Takedaite is a very rare mineral, to date (February 2022) found only at the type locality.
Localities
At the type locality, the Fuka mine, Fuka, Bitchū, Takahashi City, Okayama Prefecture, Japan, many
skarn minerals occur, such as
gehlenite, spurrite,
bicchulite, rankinite,
kilchoanite, fukalite and
oyelite. A vein, approximately 10 cm in thickness, consisting of
borate minerals, developed along the boundary between crystalline
limestone and
gehlenite-spurrite
skarn.
At the centre of the expanded area takedaite occurred as aggregates of granular crystals up to 0.8 mm long and
0.3 mm wide, in association with frolovite,
calcite and an unidentified mineral. At the circumference of the expanded area,
hydrous borates such as nifontovite,
olshanskyite, sibirskite and
pentahydroborite occurred
(MM 59.549-552). The takedaite probably formed by boron-rich fluids
reacting between crystalline limestone and the
gehlenite-spurrite
skarn
(HOM).
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