Hydrochlorborite
Hydrochlorborite is an IMA-recognized mineral species in the halide class, with the chemical formula Ca₂B₃O₃(OH)₄·BO(OH)₃Cl·7H₂O.
It crystallizes in the monoclinic crystal system (space group I2/a).
Key properties: Mohs hardness 2.5; specific gravity 1.83–1.85; Vitreous to dull luster; optically biaxial.
IMA symbol Hcb, grandfathered status — known before the IMA’s founding, named in 1965.
A rare dry-season evaporite mineral in playa sediment (Salar Carcote, Chile).
It is found associated with Ulexite, halite, gypsum (China).
In allusion to the essential chemical components, water, chlorine and borate.
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet.
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