What is Cabrerite?
Cabrerite is a hydrated nickel magnesium arsenate and a rare member of the vivianite group, usually found as pale green collector material.
Mineralogy and structure
The reference formula is NiMg2(AsO4)2·8H2O. Cabrerite belongs to the arsenates and crystallises in the monoclinic system. Cabrerite has a layered hydrated arsenate structure. The historic name “cabrerite of Dana” was used for a magnesian variety of annabergite and is kept separate from the modern IMA species here.
Colour and appearance
Typical colours include green, pale greenish and pale pinkish. For small or complex mineral species, crystal size, transparency, lustre and matrix association are often more diagnostic than colour alone.
Formation and localities
Cabrerite forms in or is associated with nickel-rich hydrothermal and secondary arsenate assemblages. Important documented localities include Nevada in the United States, Laurion in Greece and the historic Sierra Cabrera locality in Spain. A precise mine or geological setting is preferable to a broad country label when it is known.
Collecting and care
Cabrerite is best treated as a labelled reference or collector specimen. Protect fragile crystals from impact and humidity changes. Arsenic-, cadmium-, lead-, thorium- and selenium-bearing minerals should not be cut, ground or used in jewellery; wash hands after handling and keep them away from food and children.
