Colemanite Overview

Colemanite - Overview

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.

Manufacturing Process

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.

The Uses of Colemanite

Colemanite is a significant ore of boron and was the most important ore prior to the discovery of Kernita in 1926.

Non-sodium Fiberglass Industry

Colemanite is used in nonsodium fiberglass industry to make heat resistant glass

Cleaning Agent

It is used as an ore of boron and as a source of borax (a cleaning agent and useful for industrial chemical)

Other Applications

Colemanite can be used to lower flux temperature, as opacifier, and various industrial, mechanical, glass industry and cosmetics applications

Hazards Identification

Colemanite is considered as a non-hazardous material and it has not been tested for detailed occupational and toxicological studies. However, human study of occupationally exposed borate worker population showed no adverse reproductive effects.

Precautionary Statements: Obtain special Instructions before use If exposed or concerned, get medical advice/attention Do not handle until all safety precautions have been read and understood. Wear protective gloves, eye protection. Dispose of contents/container to comply with local, state and federal regulations.


CAS No12291-65-5
Molecular Weight411.09 g/mol
H.S Code2528.00.90
SynonymsHydrated calcium borate, Di-calcium hexaborate pentahydrate, Boro-calcite


AppearanceGround, light grey to tan stones granulate (80% -75 micron or 80% -45 micron)
Boiling PointNot applicable
Freezing PointNot applicable
Melting Point986 °C
Vapour PressureNot applicable
Bulk Density1460-1520 kg/m3
Solubility in Water0.81 g/l (25°C)