Olivenite, Cu2(AsO4)(OH) (Copper Arsenate Hydroxide), occurs in secondary oxidation zones of Copper ore deposits. It is frequently found associated with Malachite, Azurite, Cerussite and Cuprite. It often coats Limonite. Although once frequently found on the mine dumps in England it is now extremely rare. It often forms vertical needles in various shades of green that led to the local name "wood copper".
Description
: An elongated matrix containing several small cavities. Two of these contain a carpet of dark green botryoidal masses, which is the Olivenite. Some vertical crystals can be seen at the back of the vugs but only with magnification. On the front of the matrix is a small deposit of pale blue-green mineral which is possibly Cornwallite.
