Chalcopyrite – Copper Ores
Mineralogy – Types of deposits
There are hundreds of minerals in which copper participates with high concentrations. These minerals mainly belong in the groups of sulphides, sulphuric salts, sulphates, oxides, hydroxides, carbonates, silicates or can be found in the form of compounds with other elements (e.g. copper arsenides or selenides). Native copper must be added to these. The main minerals of copper that have an economic interest, their chemical formula, their copper content and some images of them are presented in the following Table. More than 70% of copper ores contain mainly the mineral chalcopyrite (CuFeS2). Copper ores can be found in many ore deposit types and in many places on Earth, and great importance, as future copper sources, can be given to the concentrations in the, so called, fields of nodules in great ocean dephts, as well as to deposits of compact sulfide ores that are related to volcanic activity, also in ocean areas.
The main characteristic types of copper ore are the following:
• Sedimentary copper containing ores which are guest in clay or psammites (of the Kupferschiefer type or the Zambian copper belt type).
• In complexes of alkaline igneous rocks (e.g. complex of Palabora carbonatites of South Africa).
• In terrigenous sediments (of Red bed type).
• In copper skarns which are related to granitoid intrusions.
• Compact suflide ores – in which can exist increased copper concentrations – which are related to volcanism: principally ores in lava sequences in ophiolite complexes, known as “Cyprus type” ores, as well as in volcanic sequences in island arcs, known as “Kuroko type” ores.
• Epithermal deposits of enargite – gold.
• Porfyric copper ores (which possibly contain gold).
In the area of the Carpatho-Balkans, great importance must be given to the two last types of ore, which consisted important sources of the metal, already since the Bronze Age. In some cases the exploitation still goes on – usually with the parallel extraction of gold – (e.g. the deposits of Chelopech, Assarel, Elatsite in Bulgaria, Bor and Majdanpek in Serbia, Buchim in FYROM) or is at the phase of development of a mine (Skouries in Chalkidiki) or at the phase of advanced research (Sapes in the Prefecture of Rhodope). The copper production in Cyprus has always been important, from many deposits of compact sulfide ore, which are guest in sequences of lava effusion in a pillow form in the Ophiolite complex in Troodos.
Name, chemical formula, content,
Table of copper ores
Native Copper (Cu)