Category Ore Geology

Prospecting and Exploration

Geological Indicators or Guides

i)     Geological Indicators point to the presence of mineralization in the area- float, and black sands with ore minerals, zones of wallrock alteration containing economic minerals, as well as oxidized and leached outcrops, primary and secondary dispersion haloes of host rock ore minerals and elements.

ii)   Primary Dispersion Haloes represent the entire complex of wall rock alterations and accumulations in the host rock linked with the concentration of valuable elements during endogenous and exogenous mineralization. Their role is particularly important in the search for buried deposits. Their development is governed by the same laws of endogenous and exogenous deposits...

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Summary of ore forming processes (Endogenous)

  1. Igneous processes take place in magmatic systems, and involve crystals, immiscible liquids (magma, sulphide melt, oxide melt, water), and gases (as formed when water boils). Chemical and physical processes associated with the separation of crystals or immiscible liquids from magma, give rise to magmatic fractionation, which can produce a range of igneous rock types and may concentrate metals to form ore deposits.
  1. Igneous rocks span a range of compositions – from peridotite to gabbro (basalt) to diorite (andesite) to granite (rhyolite) – the formation of which depends on the source of the magma and the extent to which magmatic fractionation has occurred...
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Geologic Settings of Ore Deposits

Many types of mineral deposit are restricted to particular geological settings. Links with particular geographic locations and geological ages are important in mineral exploration.

1. The concentration of metals to produce ore deposits involves igneous, sedimentary and aqueous fractionation by natural physical and/or chemical processes in magmatic, sedimentary and hydrothermal systems. Most of these processes occur within the rock cycle. Many are driven by plate tectonic activity.

2. Mineral deposits linked to specific tectonic settings are:

  • Podiform chromites, Cyprus- type massive sulphides and metalliferous sediments, which form at constructive plate margins but are preserved at destructive plate margins;
  • Porphyry (copper and molybdenum) ore deposits and Kuroko-type massive sulphide d...
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Economic Aspects Of Ore

  1. Due to  the vast array of properties exhibited by metals, both in their pure form and when used in combined form in alloys, chemical compounds and composite materials, metals are very important. The choice of a metal for a particular use depends on the suitability of its properties, its price and the availability of substitutes.
  1. Price of metals depend on their usefulness and the perceived value, accessibility of the ore and the cost of processing necessary for the metal to be extracted. Supply is ultimately constrained by the availability of a metal, and the distribution and extent of natural concentrations. Demand can be affected by substitution for or by other materials. Price, supply and demand are all affected by economic, technological and political factors.
  1. Metals are derived f...
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