Copper is rarely found in nature in pure metal form. The specimen on display is a very large, tree-like aggregate. It is particularly well preserved and has almost no surface oxidation. The sample comes from the famous Ray Mine complex in Arizona, about 130 km south-east of Phoenix, to this day one of the largest open pit copper mines in the world. In this typical porphyry copper deposit, Precambrian rocks, dating back more than 530 million years, have been crossed by hydrothermal fluids that have deposited various elements of economic worth, including copper. This type of deposit is the primary geo-resource for the huge demand for copper mainly from the worldwide electrical and electronic industries.
