1.1. Geologists classify mineral deposits in many different ways, according to the: • commodity being mined • tectonic setting in which the deposit occurs • geological setting of the mineral deposit • genetic model for the origin of the ore deposit
2. Economic viability of ore deposits
2.1. Many factors control the economic viability of an ore deposit but the most important are: • grade (i.e. amount of metal per ton of rock) • size of the deposit (i.e. tonnage)
3. Oxidised zones of ore deposits
3.1. The region above the water-table in an ore deposit is known as the oxidised zone as it is the zone of oxidation of the primary ore minerals
4. Finding ore deposits
4.1. Geologists are always searching for more ore deposits to meet constant demand. This has become more difficult with time as easily accessible ore deposits close to the Earth's surface have already been exploited by humans in the past.
5. Remobilisation of ore deposits
5.1. As many ore deposits formed many hundreds to thousands of millions of years ago, many have experienced numerous episodes of deformation and metamorphism which left them with few characteristics of their original form
6. Archaean gold deposits
6.1. Archaean gold deposits account for more than 60% of the world's gold. Over 60% of this comes from the Witwatersrand of South Africa
7. Epithermal gold deposits
7.1. These deposits are related to convergent-margin tectonic settings such as that of the Andes, South America
8. Sedimentary iron ore and manganese deposits
8.1. Most of the world's iron and manganese are derived from deposits of this type. These deposits are very large in size (thousands of millions of tons) and are usually mined by open-cut methods
