Modern High-Tech Prospecting

Boot-and-hammer prospecting has always been an important part of mineral exploration in Canada. But exploration has hanged dramatically with recent advances in technology, all of which play a part in the task of prospecting

Typically, geological reconnaissance begins the process. In many countries, government geological surveys employ mapping geologists, who examine large areas, making note of all pertinent geological features as revealed in outcrops and prominent landforms. The geological reports and maps they make serve as an important source of reference for the mine finder. Experienced prospectors plan their search in areas where the rocks and geological structures suggest there could be mineralization.

The first order of business for the prospector is geological mapping, on a scale more detailed than that of the government geologists, and surface prospecting.

The prospector looks for trace amounts of ore minerals, for favorable rock types, and for alteration that may have been caused by mineralizing solutions. One valuable sign of mineralization is a gossan, an area of rusty staining on rock formed when sulphide minerals are oxidized. Other ore minerals also can oxidize, leaving a surface stain of secondary minerals on host rocks. The light green of nickel bloom or the bright yellow and orange of secondary uranium minerals are examples of this.

If a showing is found, it is sampled, and the samples sent for a chemical analysis called an assay. Sampling, which will be covered in more detail in Chapter 5, can be as simple as banging off a piece of rock from an outcrop.

Often the exploration clew will bring in a bulldozer to strip away overburden or use explosives to blast a trench in the rock.

Another useful technique at the reconnaissance stage is remote sensing, the use of photographic and radar images taken by satellites or aircraft. Aerial and satellite imagery can show large-scale geological structures like faults or geological contacts in which mineralization often occurs. In some areas, such as deserts, color changes on satellite imagery may denote changes in rock type or show areas of rock alteration.

It is generally believed that tomorrows mineral discoveries in established mining areas will likely come at greater depths than known orebodies. They might also come from areas covered by heavy blankets of over burden. Finding these deposits requires more sophisticated technology than traditional prospecting methods. Buried targets can be explored by diamond drilling, but to know where to aim the drill the prospector will have to use geological inference, geo physics or geochemistry.