Gold Mining in South Africa – Dougall Fraser – 21 February ’22
Those who thought there might be some free samples handed out were disappointed; but not so with this entertaining account of his 15 years as a geologist in South African goldfields by fellow-Rotarian Dougall Fraser (Loudoun RC).
Gold was first discovered in sufficiently large quantities to warrant mining in the late 19th century. The three main operations are situated in the Witwatersrand Basin, a sedimentary Basin which is geographically located in the central north to north-eastern parts of South Africa. These began in 1886 with the recognition of gold in quartz pebble conglomerates (gravel beds – traditionally termed “reefs”), contained by a 6,000m thick sequence of principally mudstone and sandstone sediments. The Basin extends from Johannesburg in the north to some 40 kilometres south of Welkom and covers an area of approximately 30,000 square kilometres. Gold Fields’. It remains the world’s largest gold-producing region.
Anglo American, who Dougall worked for, is a global mining company who first exploited these extensive South African reefs, the success of which was primarily responsible for the massive urbanisation and growth of Johannesburg.
Dougall proceeded to give an interesting lesson in the complex structural geology of the region and the various mining techniques which were required to enable the economic extraction of the precious metal. The gold itself is found in very small quantities relative to the conglomerate rocks which contain and overly the seams. Increasing mechanisation using ever-bigger plant made it possible to strip these overlying rocks (as much as 40,000 feet deep) economically. In total some 2 billion ounces of gold have been mined from these fields which account for about 40-50% of the world’s gold and some 35% of the world’s resources still remain there. Politically, China’s influence in South African gold mining is increasing to the disadvantage of other long-established concerns.
Alex Thomson gave the vote of thanks.
Dougall with President Bob Cherry and a lump of rock.
