Olivenite is a copper arsenate mineral, formula Cu2AsO4OH. It crystallizes in the monoclinic system (pseudo-orthorhombic), and is sometimes found in small brilliant crystals of simple prismatic habit terminated by domal faces. More commonly, it occurs as globular aggregates of acicular crystals, these fibrous forms often having a velvety luster; sometimes it is lamellar in structure, or soft and earthy.
Olivenite is one of the most common minerals in the earth, and is a major rock forming mineral. Despite this, good specimens and large crystals are uncommon and sought after. Only few localities yield large examples of this mineral, although small and microscopic grains are found worldwide. Olivine is also found in meteorites, and large grains have been reported in many of them.
From Christiana Mine,Lavrion District Mines, Lavrion District (Laurion; Laurium), Attikí Prefecture (Attica; Attika), Greece