Calcium borate
3D model (JSmol)
ECHA InfoCard 100.034.131 Edit this at Wikidata
  • InChI=1S/2BO3.3Ca/c2*2-1(3)4;;;/q2*-3;3*+2 checkY
  • InChI=1/4BO3.6Ca/c4*2-1(3)4;;;;;;/q4*-3;6*+2
  • InChI=1/2BO3.3Ca/c2*2-1(3)4;;;/q2*-3;3*+2
  • [Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[O-]B([O-])[O-].[O-]B([O-])[O-].[O-]B([O-])[O-].[O-]B([O-])[O-]
  • [Ca+2].[Ca+2].[Ca+2].[O-]B([O-])[O-].[O-]B([O-])[O-]
Molar mass 237.852 g/mol
Appearance bluish white crystal
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
590 mg/kg (oral, mouse)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Calcium borate (Ca3(BO3)2), also called Gerstley[1] borate[citation needed], is a bluish white crystal with a very defined structure. It can be prepared by reacting calcium metal with boric acid. The resulting precipitate is calcium borate. A hydrated form occurs naturally as the minerals colemanite, nobleite and priceite.

One of its uses is as a binder in some grades of hexagonal boron nitride for hot pressing. Other uses are e.g. flame retardant in epoxy molding compounds, a ceramic flux in some ceramic glazes, reactive self-sealing binders in hazardous waste management,[2] additive for insect-resistant polystyrene,[3] fertilizer, and production of boron glasses.

Also it used as a main source of boron oxide in the manufacturing of ceramic frits that used in the ceramic glaze or ceramic engobe for wall and floor ceramic tiles.


  1. ^ For James Gerstley (according to, Gerstley Borate) after whom Gerstley, California is also named
  2. ^ Calcium borate binders. (PDF) . Retrieved on 2010-02-08.
  3. ^ Calcium borate infused foam building materials and the like and method of making same - US Patent 6667350 Claims Archived 2011-06-12 at the Wayback Machine. Retrieved on 2010-02-08.