EXPLORATION 101

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The initial stage of mining starts with the process of finding and the exploration of the mineral deposit. Prospecting is a small-scale form of mineral exploration.

Prospecting is physical work, involving traversing (traditionally on foot or on horseback), panning, sifting and outcrop investigation, and/or looking for signs of mineralization. In areas of known deposits (think Cripple Creek in the 1890s), prospectors may simply be looking for “color”. In the case of Cripple Creek (and elsewhere), that color was a surface vein of quartz. In some areas a prospector must also stake claims, meaning they must erect posts with the appropriate placards on the corners of the desired land they wish to prospect.

Mineral exploration is also a process of finding orebodies. Mineral exploration is a more advanced form of prospecting. The initial discovery may be made from prospecting, research of historical accounts or mineral maps, academic geological reports or local, state, and national geological reports. Mineral research may also include satellite and airborne images (including photographs and geophysical methods).

Satellite imagery is important in the early stages of exploration and is typically some of the first information obtained by anyone exploring in a new area. We can use satellite imagery from satellite systems such as Landsat, WorldView, SPOT, RapidEye and EROS. The different satellite systems differ in how often they return to the same location, how much detail they capture and the number of different colors they record. Satellite systems capture the red, green and blue bands of the visible spectrum, but they may also capture colors in the near-infrared and shortwave infrared bands, well beyond the visible spectrum. Geologists get a double benefit from using these multispectral images because shortwave infrared bands are sensitive to changes in soil and rock content, making it possible to differentiate some basic rock types.

In airborne geophysics, magnetic surveys, for example, may be used to sample the earth’s magnetic field. These surveys make it possible to gather detailed information about the presence of various magnetic and non-magnetic materials in the earth’s crust. Electromagnetics, another airborne geophysical method, is a technology for mapping variations in subsurface conductivity, which is used in identifying massive sulfides, graphite, and kimberlite pipes.

Once orebodies are identified, the work my shift from this hand’s-off form of exploration, to an on-the-ground form of exploration, which usually includes land-based forms of geophysics and exploratory drilling. This stage of exploration takes time and money, and the effort is focused on assessing whether or not you might have an orebody that could be viably mined. At some point, as the exploration proceeds, fairly large teams of engineers and scientists become involved in the assessment. This would include geotechnical engineers, environmental and permitting people, metallurgists, plant designers, mining engineers, geologists and more.

There is quite a bit of activity that goes into the exploration of an orebody.

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