Class : Silicates
    Subclass : Phyllosilicates
    Crystal system : Orthorhombic
    Chemistry : CuSiO₃.2H₂O
    Rarity : Common

Chrysocolla is a secondary silicate found in the oxidation zone of copper deposits. It is the most common copper silicate, it can hold up to 9% water. It owes its name to the Greek khrusos (gold) and kolla (glue), because this mineral was formerly used for the welding of gold. It is usually cryptocrystalline mass concretized stalactitiform to shapeless, earthy coatings or encrustations, sometimes adopting an opal or enamel appearance. The crystals are very rare, acicular. The chrysocolla has hues spread throughout the range of greens and blues, has a vitreous, porcelain or earthy sheen and a typical conchoidal fracture. Its density is variable because of frequent mixtures with opal and other silicates, phosphates or oxides of copper. In addition to their occasional role as copper ore (Nijni Taguil in Russia, Arizona, Boleo in Mexico), the chrysocollas veined or banded, particularly aesthetic have a use as gemstones or ornamental stones, in this case it is often closely intertwined with chalcedony, which gives it sufficient hardness for the cutting and malachite and azurite that enhances its color.

In France, we find the chrysocolla anecdotally. It is reported in Crozet (Loire), Lantignié, Longefay, Chessy and Propières (Rhône), Argentolle and Molérats (Saône-et-Loire) or Montroc in the Tarn.

The chrysocolla can pseudomorph other species such as malachite or azurite.

Some polished stones or some nodules of magnesites or others can be coated with green resin and sold for chrysocolla although these practices are rather intended to imitate turquoise...