What is Valleriite?
Valleriite is a soft layered copper-iron sulfide associated with ultramafic rocks and nickel-copper ore systems, recognised by bronze colour and platy habit.
Mineralogy and structure
Reference formula: Cu2Fe4S7. Valleriite has a layered orthorhombic structure and commonly contains variable copper, iron, magnesium and sulfur. The exact COD 1011125 model is used, but specimen chemistry may be complex. Valleriite is classified with sulfides and has orthorhombic crystal symmetry. Typical hardness is 1–2 on the Mohs scale and specific gravity is approximately 3.8–4.2.
Colour, lustre and habit
Typical colours include bronze, brass-yellow, brown, black. The usual platy, scaly, massive habit and metallic, dull lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Valleriite forms in or is associated with serpentinised ultramafic rocks, magmatic sulfide deposits and hydrothermal nickel-copper systems. Important documented localities include Sweden, Canada, Russia, Norway, South Africa and the United States.
Bronze sheets from a nickel-copper system
Valleriite is a specialist ore mineral whose value comes from texture and geological context. A platy bronze specimen can show the layered chemistry of a deep ultramafic environment.
Collecting and care
Soft and sulfide-bearing: keep dry, avoid dust and acids, and do not cut or grind without professional controls.
