2.2.6 Diamond Drilling

For many years, uncertainty persisted as to the extent and value of deposits that were often discovered by chance, as a result of outcrops or trenches dug in the course of public works, such as railways.

The prospector had to rely on the contents of the samples he took from the surface. The only way he could find out more was to dig a trench in the outcrops, an open-pit mine or drifts along the lodes located at the surface.

		Engraving of Acton Mine 1860.
	Source

As of the 1920s, prospectors and mining companies in Quebec started to systematically use diamond drilling.

		Diamond drilling installations: Lac Osisko.
	Source

Diamond drill.		Core splitter.		Core samples and wooden boxes.
Source		Source		Source

This innovation had considerable repercussions on prospecting and mining exploration activities. Positive clues at the surface, such as magnetic anomalies, could now be confirmed or invalidated by analysing core samples taken from the depths. The shape and composition of deposits could be determined without any visible indications on the surface.

		Drilling installations in the forest: Chibougamau region, 1969.

Drilling installations in the forest: Chibougamau region, 1969. Source

Core sample boxes, Chibougamau region, 1969 Source

The transportation and operation of the required machinery caused prospecting costs to rise sharply. In the 1920s, prospecting was increasingly financed on the stock markets and investors followed survey results and development prospects closely. The copper and gold deposits discovered in Northwest Quebec in the 1920s and 1930s owe much to this new technology.