Significant economic mineral deposits are more difficult to find than other natural resources such as forests and land suitable for agriculture. Deposits have to be discovered. They are fixed in location, which means that they are not necessarily found in convenient areas. They are also fixed in size and quality which determines when and how they can be developed.
Even the largest deposits are very small compared to the areas that have to be explored to find them. The exploration tools of the past such as picks, shovels and bulldozers that were used to locate the deposits near the surface are of limited value in this deeper search. It is possible that some new deposit styles may still be found near the surface. However, the trend will continue to be towards exploration for concealed mineral deposits located at considerable depth.
The search for deeper mineral deposits presents a major challenge for today's mineral explorers. While exploration technology has become more sophisticated and complex, its environmental impact has been reduced. Every exploration program is different and there are no hard and fast rules governing the process and the outcome. However most programs are structured around three fundamental stages:
- Area selection
- Data gathering
- Data evaluation
The process of area selection and initial area evaluation is influenced by knowledge of the geology of known mineral deposits around the world and the identification of other areas that are thought to contain similar geological features. Some areas are regarded as more prospective for various deposits than others.
Area selection is usually an office task with minimal field work. In Western Australia, as in most developed countries, Government produced regional geological and geophysical plans provide a basic outline of the State's geological framework. Records of previous exploration are also available.
Once an area has been selected, the explorer must apply to the State Government for the right to explore the area. If this is granted, the explorer can begin gathering data.
Much of the early reconnaissance phase of exploration is by remote sensing methods including satellite imagery, conventional and infra-red aerial photography and airborne geophysical surveys from helicopters or fixed wing aircraft. Such techniques have virtually no environmental impact as they do not have any contact with the land surface.
If the results of remote sensing are encouraging, ground surveys may be initiated. These can involve the use of geological mapping, geochemistry of surface materials and geophysics. This work is aimed at defining small areas of heightened interest that may warrant further testing by drilling.
The presence of concealed mineral deposits can only be confirmed and outlined by drilling. Other techniques merely indicate the possible presence of a deposit.
At this stage of exploration, results are assessed and the exploration geologist decides whether to proceed with further work. Of every one thousand exploration programs initiated only ten reach the deep-drilling stage and only one leads to a major mineral deposit discovery.
There are many examples of major mineral deposits being discovered in areas explored on several previous occasions. Re-evaluation of previously explored areas is very important in the search for minerals.
Reference : Mineral Exploration "The future of the Mining Industry in Western Australia" by DR M.J. DONALDSON
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