Huntite

Huntite is a carbonate mineral with the chemical formula Mg₃Ca(CO₃)₄. Huntite crystallizes in the trigonal system and typically occurs as platy crystals and powdery masses.

Discovery

In 1953 a paper by George Faust announced the discovery of a new carbonate mineral found in Currant Creek, Nevada (USA). Faust acknowledged that the mineral probably had been discovered previously, but had been misidentified as impure magnesite by W. E. Ford in 1917. Faust named the new mineral "huntite" in honour of his former teacher, Walter Frederick Hunt (1882–1975) , Professor of Petrology at the University of Michigan. Faust carried out analyses of the mineral, and found amongst others that in differential thermal analysis huntite showed two endothermic peaks, which could be attributed to the dissociation of MgCO₃ and CaCO₃ respectively. Chemical analyses showed huntite to consist of Mg₃Ca(CO₃)₄.

Properties

Huntite often occurs in combination with other Mg/Ca carbonates such as dolomite, magnesite, and hydromagnesite. Large deposits of huntite occur in Turkey and Greece and these are commercially exploited because of its fire retardant properties. Huntite thermally decomposes over a temperature range of about 450–800 °C, releasing carbon dioxide and leaving a residue of magnesium and calcium oxides.