http://b4hntuy3fimfh2227vf4f74emnya7p35i5brtqujs6leqvtclfwvjbqd.onion/doc/physics/diamonds-crookes/The%20Project%20Gutenberg%20eBook%20of%20Diamonds,%20by%20William%20Crookes..html
The Kimberley
Mine seems to have presented a slight
elevation above the surrounding flat country,
while the sites of other mines were level or
even slightly depressed. The Wesselton
Mine, within a mile of Dutoitspan, has only
been discovered a few years.