"Cullinan" - A visit to a Diamond mine

Mining is a very important part of South Africa's identity and economy. Gold, diamonds, platinum, iron ore, coal - the country is blessed by nature, above ground in its climate und fertility, and underground, in its geology with its mineral deposits. This natural richness is one of the reasons, why this land has been so hotly contested by so many people over the last few centuries.

Panorama view of Pretoria from the Union Buildings, Government Avenue.

One hour north of Johannesburg a little bit east of Pretoria one can visit an active diamond mine, the Cullinan Diamond Mine. During working hours on weekdays one can even go down a shaft over 700 m deep to see work underground. I went on a Sunday and took the very interesting surface tour of the mine.

these cables on huge winders hold the pit cage

Diamonds have been found in South Africa since the end of the 19th century. In 1902 an accidental find of a rough diamond on farmland led to the establishment of an open pit mine at Cullinan in 1903. Only two years later, in 1905,  the biggest rough diamond so far, the "Cullinan" with 3106 carat, was found there in 9 m depth.
The Cullinan mine sits on a volcanic carrot shaped funnel called "pipe" full of a substance called kimberlite. Brown kimberlite contains most gem grade diamonds. 

Model of the volcanic shaft

 the open pit

Diamonds are only produced under very special conditions very deep underground and would not normally come to surface. Here, a volcanic eruption has brought the gems to a depth that can be exploited. 

Over 4500 ct are found every day, 20 % of gem quality, the rest for industrial uses. The famous "Cullinan" diamond  was "given" to the British crown and now decorates the crown jewels. 

About ten years ago the mine was sold by DeBeers to Petra Diamonds. A few years later a very large rough diamond was found under this conveyor belt. It had fallen off the belt which brings the crushed lighter rock to the mine dumps. It sold to a Japanese jeweler for 35 Mio. $. Once the pit is empty, these dumps need to be reexamined... 

Out at last and ready to shine!