Chrysocolla, beautiful cut pieces from Peru.

The mineral chrysocolla is a hydrated copper-aluminum silicate with the chemical formula (Cu,Al)2H2Si2O5(OH)4·n(H2O). The mineral belongs to the cyclosilicates. The translucent to opaque green, blue, blue-green or brown chrysocolla has a dull to glass luster, a light green stripe color and the mineral does not split. Chrysocolla has an average density of 2.15 and the hardness is 2.5 to 3.5. The crystal system is orthorhombic and the mineral is not radioactive. Similar minerals include dioptase, shattuckite and turquoise. The name of the mineral chrysocolla is derived from the Greek words chrysos ("gold") and kolla ("glue"). This name was given because the mineral was used to solder gold. Chrysocolla is a fairly common mineral that occurs mainly as an accompanying mineral of copper ores. The type locality is Nizhne-Tagilsk in the Urals, Russia. There are significant concentrations in the United States, mainly in the states of New Mexico, Nevada, Arizona, Idaho and California. This mineral is also found in Mexico, Chile, Peru and Canada. Very beautiful stones come from Israel, South Africa, Congo, Zimbabwe, Russia, Kazakhstan, Moldova, Germany, England, Romania and France. Eilat stone is a growth of chrysocolla with turquoise and malachite, found near Eilat in Israel. Chrysocol quartz is a growth of chrysocolla with quartz.