Mineral Ore Deposits
Ores are minerals or rocks with concentrations of elements that can be economically extracted.
- Associated with igneous intrusions and metamorphic processes.
- Superheated water, often rich in salts, dissolves minerals.
- The fluids move through fractures and joints in rock.
- These transported minerals are deposited or precipitated in surrounding rock or within the rock voids (veins).
- Examples: pyrite (FeS2), galena (PbS), cinnabar (HgS), sphalerite (ZnS), covellite (CuS). Metals are often deposited as sulphides.
- Metamorphic examples: Marble
- As intrusions cool, minerals form at different rates and specific temperatures.
- Early forming minerals may sink within the intrusive body.
- Examples: Chromium and platinum deposits in South Africa.
- Minerals segregate due to chemical and physical sedimentary processes.
- Placer deposits: gold and titanium.
- Evaporate examples: gypsum (CaSO4 · 2H2O) and halite (NaCl)
- Precipitate examples: phosphate rock, limestone (CaCO3) and BIF