Copper is one of the most important and oldest metals known to humans. It is the main metal in electrical engineering, the material for wires, cables, windings of electric motors, generators, and transformers. However, this well-known and common metal is not so much on Earth. The average content of copper in the earth's crust is 0.01%, which is 2 times less than, for example, vanadium or chromium. But copper, unlike many other metals, forms a full range of ore minerals, from which it is convenient to extract it. More than 240 copper minerals are known in nature.
Native copper occurs in small quantities and is of interest only as a mineralogical rarity. It is formed in the zone of oxidation of copper sulphide deposits and in the voids of basaltic lavas. Clear crystals of native copper in the form of small cubes with blunt edges and tips are rare. For the most part, these are dendrites, complex intergrowths of crystals that have grown in cramped space, and in shape they resemble the branches of a fern or some kind of coniferous tree (in Greek, “δένδρον” is a plant). Some of the most beautiful copper dendrites in the world are found in the Urals, in the region of the Turya mines. Nuggets from the oxidation zones sometimes reach significant sizes.
Sample of native copper