Strontioborite

strontioborite

bischofite

halurgite

ginorite

Images

Formula: Sr[B₈O₁₁(OH)₄]
Anhydrous hexaborate, strontium-bearing mineral
Crystal System: Monoclinic
Specific gravity: 2.40 measured, 2.35 calculated
Hardness: 2½
Streak: White
Colour: Colourless
Luminescence: Not fluorescent under UV or an electron beam
Solubility: Insoluble in water
Environments

Salt dome

Strontioborite was reported in 1960, first discredited then re-approved in 2020. To date (December 2024) it has been reported only from the type locality.

Localities

The type locality, the Chelkar salt dome, Aksai Valley, Shalkar District, Aktobe Region, Kazakhstan, is the only known locality for strontioborite; it occurs in halite rocks with bischofite, magnesite, anhydrite, halurgite, boracite, ginorite and celestine. It forms colourless lamellar, scaly or tabular crystals up to 2 mm across (MM 88.5.585-593).

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