What is Cacoxenite?
Cacoxenite is a hydrated iron aluminium phosphate recognised by golden-yellow to orange fibrous sprays and silky crusts.
Mineralogy and structure
The reference formula is Fe24AlO6(PO4)17(OH)12·75H2O. Cacoxenite belongs to the phosphates and crystallises in the hexagonal system. The mineral is extremely hydrated and commonly forms acicular or fibrous aggregates rather than large isolated crystals. It belongs to the hydrated phosphates and should be protected from impact and drying.
Colour and appearance
Typical colours include yellow, golden yellow, orange, brownish yellow and green. For small or complex mineral species, crystal size, transparency, lustre and matrix association are often more diagnostic than colour alone.
Formation and localities
Cacoxenite forms in or is associated with oxidised phosphatic iron deposits, phosphate-rich pegmatites and iron-rich sediments. Important documented localities include the Czech Republic, Brazil, the United States, Sweden and Ireland. A precise mine or geological setting is preferable to a broad country label when it is known.
Collecting and care
Cacoxenite 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.
