What is Cobaltocalcite?
Cobaltocalcite is a pink cobalt-rich variety of calcite, prized for vivid colour and attractive crystals from oxidised cobalt-bearing deposits.
Mineralogy and structure
The reference formula is CaCO3. Cobaltocalcite belongs to the carbonates and has a trigonal crystal system. Cobaltocalcite uses the trigonal calcite structure; cobalt substitutes for part of the calcium and produces the characteristic pink colour. It should be presented as a calcite variety rather than a separate species.
Colour and appearance
Typical colours include pink, rose pink, purple-pink. Crystal habit, lustre, transparency and matrix association are often as diagnostic as colour.
Formation and localities
Cobaltocalcite forms in or is associated with oxidised zones of cobalt-rich hydrothermal veins and carbonate replacement deposits. Important documented localities include Bou Azzer in Morocco, the Democratic Republic of the Congo, Mexico and selected cobalt districts.
Collecting and care
Cobaltocalcite is best kept as a labelled collector or reference specimen. Protect fragile crystals from impact and prolonged humidity changes. Lead-, arsenic-, chromium- and cobalt-bearing minerals should not be cut, ground or used in jewellery.
