Colemanite or hydrated calcium borate (Ca2B6O11.5H2O) is a colorless or white monoclinic crystal which formed by the evaporation of deposits together with other borates. Colemanite is a secondary mineral which derived from borax and ulexite. Colemanite is a common natural source of insoluble boron and also one of the more stable borate mineral.
Colemanite is enriched via crushing, wetting in water, washing in a thumbling, sieving, triage and classification. Colemanite forms at a lower pH and warmer temperature than other borates.
Colemanite is a significant ore of boron and was the most impoertant ore prior to the discovery of Kernita in 1926.
Colemanite is used in nonsodium fiberglass industry to make heat resistant glass