Boracit, Mineralogisches Museum Bonn — Photo: Elke Wetzig (Elya) · CC BY-SA 3.0
Boracite
A magnesium borate-chloride forming orthorhombic crystals that mimic cubes and octahedra — colors range from blue-green to white.
Intro adapted from Wikipedia (CC BY-SA).
Boracite is an IMA-recognized mineral species in the halide class, with the chemical formula Mg₃B₇O₁₃Cl.
It crystallizes in the orthorhombic crystal system (space group Pca2_1). It is a member of the Boracite structural group.
Key properties: Mohs hardness 7–7.5; specific gravity 2.91–3.1; typically white or gray or yellow or green or blue; White streak; Vitreous to adamantine luster; refractive index 1.665; optically biaxial.
IMA symbol Boc, grandfathered status — known before the IMA’s founding, named in 1789.
An uncommon component of bedded sedimentary salt and potash deposits of marine origin, the boron probably derived from nearby volcanic activity.
It is found associated with Anhydrite, gypsum, halite, sylvite, carnallite, kainite, hilgardite.
The name refers to boron in the composition.
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