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Formula: Mg3(BO3)(OH)3
Anhydrous borate containing hydroxyl, forms a series with
fluoborite
Crystal System: Hexagonal
Specific gravity: 2.89 measured, 2.872 calculated
Hardness: 3½
Streak: White
Colour: Colourless
Solubility: dissolves in concentrated sulphuric acid but not in water or dilute hydrochloric acid (AM 94.1078)
Environments
Localities
At the type locality, the Titovskoe B deposit, Tas-Khayakhtakh Range, Dogdo River Basin, Polar Yakutia, Sakha Republic, Russia,
hydroxylborite occurs in the mineralized marble adjacent to the
suanite - kotoite -
ludwigite boron ore. Most of the ore is
calcite and clinohumite, but some sections are
enriched in hydroxylborite, which itself is often replaced by fibrous szaibélyite,
and sometimes ludwigite occurs as inclusions in the hydroxylborite (AM 94.1078).
Associated minerals include calcite, dolomite,
magnesium-rich ludwigite, kotoite,
szaibélyite, clinohumite,
magnetite, serpentine and
chlorite
(HOM).
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