State-guaranteed mine ownership and scientific racism entrenched white labor monopolies

Evidence

Not a moment too early minerals were discovered, and in large deposits: diamonds (1867) in Griqualand, close to the northern Cape border, and then gold in the Transvaal (in small deposits in 1870, but extensive findings by 1886). More or less guaranteed by government both at the Cape and in the boer republics, mine ownership inevitably came under white control. Fueled by connection to British traditions of union organizing and scientific racial inferiorization of non-whites, white mine-workers in South Africa managed to secure skilled positions largely for themselves, and to restrict blacks mostly to unskilled mine work. — David Theo Goldberg, The Threat of Race, 1442