Devilline

Devilline is a rare mineral composed of hydrated copper and calcium sulfate (CaCu₄(SO₄)₂(OH)₆·3H₂O), belonging to the sulfate group. It usually occurs as small tabular crystals or in aggregates, with colors ranging from pale green to emerald green.

It forms in the oxidation zones of copper deposits, often associated with malachite, azurite, brochantite, or chrysocolla. Its delicate crystals and rarity make it a prized mineral among collectors.