What is Liroconite?
Liroconite is a soft blue-green hydrated copper aluminium arsenate, prized for vivid colour and scarcity in historic copper districts.
Mineralogy and crystal structure
Reference formula: Cu2Al(AsO4)(OH)4·4H2O. Liroconite is a monoclinic hydrated arsenate with a complex heteropolyhedral framework. It commonly forms small crystals or crusts with turquoise to green-blue colour, and its softness makes surface preservation especially important. Liroconite is classified with arsenates and has a monoclinic crystal system. Typical hardness is 2–2.5 on the Mohs scale and specific gravity is approximately 2.9–3.0.
Colour, lustre and habit
Typical colours include blue, green, blue-green, turquoise. The usual prismatic, tabular, botryoidal habit and vitreous, pearly lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Liroconite forms in or is associated with oxidised copper deposits with arsenic- and aluminium-bearing solutions. Important documented localities include Cornwall in the United Kingdom, Ireland, Germany, France and Australia.
Turquoise colour with a Cornish classic locality
Liroconite is a specialist collector favourite because its blue-green colour is intense but its crystals are often small and delicate. Specimens from Cornwall carry an additional historical layer, linking mineral collecting with the old copper-mining landscape.
Collecting and care
Very soft and arsenate-bearing: keep in a closed display, avoid dust, acids, water and all cutting or grinding.
