Chambersite

chambersite

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Formula: Mn3B7O13Cl
Anhydrous megaborate, boracite group, manganese-bearing mineral
Crystal System: Orthorhombic
Specific gravity: 3.49 measured, 3.48 calculated
Hardness: 7
Streak: White
Colour: Colourless to deep purple, darkens with exposure to sunlight
Solubility: Insoluble in water
Environments

Salt domes

Chambersite occurs in brine residues from extraction wells in salt domes. Associated minerals include halite, anhydrite and gypsum (HOM).

Localities

At Penobsquis, Cardwell Parish, Kings county, New Brunswick, Canada, chambersite was found in only one sample in a drill core from the marine evaporite deposit. It was found in orange halite associated with hydroboracite, hilgardite, volkovskite, szaibélyite, anhydrite, a mica group mineral, magnesite and quartz. It occurs as 0.5 to 1.5 mm, euhedral, light blue, flattened tetrahedra (CM 43.1469-1487).

At the type locality, Storage Well No. 1, Barbers Hill Salt Dome, Mont Belvieu, Chambers County, Texas, USA, chambersite is present in brine returns from the well, probably originating in the main salt mass at a depth between 2,32O and 2,72O feet below sea level. Associated minerals include halite, anhydrite and gypsum.
The salt mass is known to intrude sediments ranging in age from Pleistocene (2.58 million to 11,700 years ago) to Late Cretaceous (100.5 to 66 million years ago), and it is capped by porous rock consisting of limestone, gypsum and anhydrite. Open spaces contain varying amounts of crystalline sulphur, pyrite and calcite.
Chambersite occurs in subhedral to euhedral crystals ranging from less than 1 mm to 1.2 cm on an edge (AM 47.665-671).
Chambersite from the Barbers Hill Salt Dome - Image

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