|Stunning Olivenite Crystals on Conichalcite From Greece. Photo Tóth László|
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.
Olivenite is a copper arsenate mineral, formula Cu₂AsO₄OH. It crystallizes in the monoclinic system, and is sometimes found in small brilliant crystals of simple prismatic habit terminated by domal faces.
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.
Crystal habit: Fibrous, globular and reniform; granular, earthy, massive
Color: Olive green to yellow or brown, gray-green, grayish white
Mohs scale hardness: 3
The specimen in the photo is From Christiana Mine,Lavrion District
Mines, Lavrion District (Laurion; Laurium), Attikí Prefecture (Attica;