Types of Copper Deposits

The Swedish copper ores in the Skellefte field have been formed in just the described way. Hydrothermal solutions streamed out over the sea bottom in a region with much volcanic activity round 2000 miUion years ago. A metamorphosis followed and created the deposits of our day, distinguished mainly by copper but also with gold and silver The old mine in Falun has a similar origin. 

Important copper deposits may also have been formed by conventional sedimentation on ancient sea bottoms without volcanic activity. In present times they appear stratiform, i.e. composed of layers in the rock. Large deposits of this type are characteristic of the so-called copper belt in Zambia and the Democratic Republic of Congo- 

Other sedimentary ores are day and carbonate-containing shales and sandstones, with 1.5-2.5% copper. They are mined in Central THrica with cobalt as an important by-product Similar shales, yet with lower copper content exist over wide areas in Germany and Poland and have been mined there for centuries. Mansfeld was such a center. 

Copper is also present in many nickel ores, from which it is won as a by-product. The largest and most famous is the deposit at Sudbury in Canada. 

---