Exploration for Metals

Basic Concepts and Techniques

Geological prospecting is an active search for minerals, including metals, from natural sources.
The process is guided by understanding of the geology of an area including structures and rock types.
Geochemical prospecting is a common technique in which soil and rock samples are analysed for traces of valuable metals.
Geophysical prospecting is another technique that uses technology to determine physical properties of rocks to identify mineral deposits. Techniques include magnetic, seismic, gravity and resistivity surveys.

Mineralisation is the process by which valuable minerals are concentrated into economically viable deposits.
It often results from processes such as igneous activity, metamorphism, weathering and hydrothermal alteration.
Understanding how these processes lead to the formation of metallic deposits is key to exploration.

Vein deposits are a major source of metallic ores. They are systems of cracks in rocks filled in by mineral-rich hydrothermal fluid.
Common metals found in vein deposits include gold, silver, copper, lead and zinc.

Placer deposits contain valuable minerals that have been concentrated by mechanical weathering and sorting of rock material.
These deposits are typically found in sediment in river channels, beach sands or other environments where running water is present.
Such deposits are sources of dense and resistant metals such as gold, platinum, tin and tungsten.

Porphyry deposits are large, low to medium grade deposits of copper associated with intrusive igneous rocks.
They form in subduction zones where fluid from the melting subducted plate rises and triggers the precipitation of metal-rich sulphides.

In economic geology, the term ‘exploration’ often involves not only the search for resources, but also the evaluation of a deposit’s economic viability.
Economic viability depends on factors like the grade and size of the deposit, depth, ore price, extraction costs, and environmental liabilities.
The environmental impact of mining operations is an important concern. This includes land degradation, water pollution, and the release of harmful substances such as heavy metals and radon gas. Responsible mining practices aim to mitigate these issues.