Adamite crystals. — Photo: Ks0stm · CC BY-SA 3.0
Adamite
A zinc arsenate that forms in the weathered zone above zinc ore bodies; pure crystals are colorless but iron traces usually tint them yellow.
Intro adapted from Wikipedia (CC BY-SA).
Adamite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Zn₂(AsO₄)(OH).
It crystallizes in the orthorhombic crystal system (space group Pnnm). It is a member of the Andalusite structural group.
Key properties: Mohs hardness 3.5; specific gravity 4.32–4.48; typically yellow or green or colorless or pink or purple or blue; white streak; Vitreous luster; refractive index 1.742; optically biaxial.
IMA symbol Ad, grandfathered status — known before the IMA’s founding, named in 1866.
Found as a secondary mineral in the oxidized zone of zinc- and arsenic-bearing hydrothermal mineral deposits.
It is found associated with Smithsonite, hemimorphite, scorodite, olivenite, calcite, quartz, Fe–Mn oxides.
The mineral was named to honor Gilbert-Joseph Adam (1795–1881), French mineralogist, who supplied the first specimens.
Collections: Collector Favorites, Fluorescent & Glowing.