What is Devilline?
Devilline is a hydrated copper sulfate hydroxide that forms vivid green to blue-green crusts and rosettes in oxidised copper deposits.
Mineralogy and structure
The reference formula is CaCu4(SO4)2(OH)6·3H2O. Devilline is soft and hydrated, so colour and surface form can deteriorate with rough handling or unsuitable humidity.
Colour and appearance
Typical colours include green, blue-green. Its platy, rosette, botryoidal habit and vitreous, pearly lustre are useful descriptive features, but colour alone is not diagnostic.
Formation and localities
Devilline forms in or is associated with secondary oxidation zones of copper sulfide deposits. Important documented localities include Cornwall, England, Mexico, Chile, the Democratic Republic of the Congo and the United States.
Collecting and care
Devilline is best kept as a labelled reference or collector specimen. Protect fragile crystals from impact and avoid cutting or grinding unknown material. Lead-, arsenic-, vanadium- and copper-bearing specimens are for display and careful handling only.
Devilline in popular symbolism
Some modern crystal guides associate Devilline with zodiac signs or symbolic themes based on colour, locality or collecting tradition. These associations vary between sources and are cultural interpretations, not mineralogical or medical properties.
