The discovery of the Kimberley Mines has been described above. The final one of five major mines to be discovered was the Wesselton Mine (previously called the Premier Mine, and not be confused with the Premier Mine (now Cullinan Mine) at Cullinan near Pretoria. Wesselton was discovered in 1891.
The original surface outcrop was approximately 4 ha in area, and from historic descriptions it formed a low hill of whitish coloured rock, today interpreted to be the calcretized cap of surface kimberlite.
Rapid mining led to the kimberlite being mined out and the mine closed by 1914. This means that no modern geological investigations were ever carried-out on probably the “archetypical” kimberlite. Maps of the mine show that it had a pipe-like shape, and that it probably consisted of diatreme-facies kimberlite.
The “west-end” portion of the mine yielded abundant brown stones of generally inferior quality as well as smoky, cracked sharp-edged octahedral diamonds. The northern portion of the pipe produced mostly boart, the north western sector peculiar brown stones, and the central and southern portions yielded high proportions of cleavage fragments.
Kimberley Mine. The distinctive features being the low abundance of boart, the rarity of white stones with white cleavage, the rarity of large macles, the presence of dodecahedral fancy stones with a deep yellow colour and a greater abundance of large yellow diamonds. He also noted that the low ........