Anhydrous normal carbonate, barium-bearing mineral
Crystal System: Trigonal
Specific gravity: 3.956 measured 3.695 calculated
Hardness: 3 to 4
Colour: White to ivory, very pale yellow, pale yellowish brown
Luminescence: Red or yellow fluorescence in short wave and long wave UV and X-rays, red phosphorescence (Mindat)
Solubility: Soluble in hydrochloric acid
Benstonite is found in baryte deposits.
At the Bayan Obo deposit, Bayan Obo, Bayan Obo mining district, Baotou City, Inner Mongolia, China, benstonite occurs in Alpine veins cutting a carbonatite. Associated minerals include huntite, barytocalcite, strontianite, pyrite, phlogopite, monazite and daqingshanite-(Ce) (HOM).
At the type locality, the Baroid Sales Division pit, Baroid Mine, Chamberlain Creek Valley, Magnet Cove, Hot Spring county, Arkansas, USA, benstonite occurs in the baryte mine, as white to ivory masses up to 1 cm in size as fissure fillings, associated with quartz, baryte and calcite (AM 46.1517).
At the Minerva No. 1 Mine, Ozark-Mahoning group, Cave-In-Rock Mining Sub-District, Hardin County, Illinois, USA, benstonite is associated with calcite, alstonite, fluorite and sphalerite (HOM).
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