Tunellite

tunellite

ulexite

kurnakovite

montmorillonite

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Formula: SrB₆O₉(OH)₂.3H₂O
Hydrated borate containing hydroxyl, strontium-bearing mineral
Crystal System: Monoclinic
Specific gravity: 2.40 measured, 2.391 calculated
Hardness: 2½
Streak: White
Colour: Colourless, greyish white
Solubility: Soluble in cold dilute acid or strong alkaline solutions
Environments

Evaporite deposits

Localities

At the type locality, the U.S. Borax Mine, Kramer Borate deposit, Boron, Kern county, California, USA, tunellite occurs as white, compact fine-grained nodules and as prismatic and tabular colourless crystals up to 1.5 cm in length as a secondary mineral in the open pit, and also in the Furnace Creek area, Death Valley, Inyo county, California (AM 47: 414-420).
Associated minerals include ulexite, stibnite, realgar, montmorillonite, kurnakovite, inderite, analcime and adularia (Mindat)

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