Anhydrous borate containing hydroxyl, forms a series with fluoborite
Specific gravity: 2.89
Solubility: dissolves in concentrated sulphuric acid but not in water or dilute hydrochloric acid (AM 94.1078)
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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