Public diamond mines
Diamonds are millions of years old. Diamonds were formed at least 990 million years ago at a depth of 125-200 kilometers below the Earth’s surface where the pressure is around fifty thousand times that of atmospheric pressure at the Earth’s surface. Through the intense pressure and heat carbon is crystallized.
In the Earth’s upper mantle, the pressure of magma cracks the surrounding rock around 125 km below the Earth's surface. The magma contains dissolved carbon dioxide, which begins to bubble and expand. This expansion causes the magma to erupt explosively up through the cracks, like an uncorked champagne bottle. The resulting explosion is vastly more powerful than most volcanoes, with molten rock rising to the surface at the speed of sound, forming a ‘pipe’.
The magma rises so quickly that diamonds do not have time to convert to graphite, which is the more stable form of carbon at the Earth’s surface. Once the diamonds cool down, they don’t have enough energy to re-form their crystal structure into graphite. The volcanic cone eventually cools and the magma hardens into “Kimberlite” or “Blue Ground”. Rough diamonds can be found in every shape of size.
Today diamonds are mined on 4 continents, namely Asia (the cradle), Africa (the profitable champion), North –America and Oceania. On each of these continents you can find public diamond mines with a history worth mentioning. We begin our journey in South Africa. Not because the cradle of diamonds is found here but because the discovery of diamonds in South Africa marks the beginning of the era of the modern diamond and it brought this fascinating gem within the reach of everyone.
In 1866 the discovery of diamonds in South Africa unleashed a true storming. In the proximity of the mines the cities shot like mushrooms from the ground. The country was divided into lots, so –called Kimberley diamond mineclaims. They wanted to give everybody a fair shot so a race was organized and in order of rank the claims were divided. In other parts of Africa they discovered even more deposits. The most famous mine of South Africa is the Kimberley mine.
In 1866, Erasmus Jacobs found a small white Pebble on the banks of the Orange River, near “Hope Town”. The Pebble proved to be a diamond of 21.00 ct. In 1871, an even larger diamond of 83.50 carats was found on the slopes of Colesberg. These findings led to a diamond rush in the area. The miners came from every corner of the country and their numbers were in the thousands, this made that the Hill swiftly disappeared, and came to be known as “The Big Hole”. The British, who had large parts of South Africa under their reign, were quick to add the area with the mine to their territory.
The Beers is the largest company who exploited this diamond mine. Very quickly, Kimberley was the largest city of the area. The immigrants were received with open arms, because the company of The Beers was looking for cheap labor. There were 5 large holes dug in the Earth. “The Big Hole” had a size of 170.000 m ² and reached a depth of 240 m. During the exploitation of this mine 3 tons of diamonds were cultivated. The mine was closed in 1914. The 3 other holes – Du Toitspan, Wesselton and Bultfontein remained open until 2005.
In 1948 layers of diamond were discovered in Russia and Eastern Siberia. One of the mines in Eastern Siberia was the Mine Mir. The mine is an abandoned open pit within the established mine Mirny. The mine is 525 m deep and has a diameter of 1.200 m. It was the first and one of the largest diamond pipes of the USSR. The Mine Mir was discovered on the 13 of June 1955 by Soviet geologists Yuri Khabardin, Ekaterina Elagina and V.Avdeenko. The mine had been active for almost 50 years before they decided to permanently close it in 2004. During the years that the mine was active, there were around 2 million carats of diamonds annually cultivated. The transport of the diamonds had always been a cause of difficulty because it took the trucks nearly 2 hours before they reached the top of the mine.
According to Jean-Baptiste Tavernier, Tieffenthaler was the first European who visited the mines of Panna. Tieffenthaler was of opinion that no other mine in India could deliver livelier diamonds than those of the Panna mines. Though this region is not known for delivering large diamonds. The mines with the most production were localized in Sakaria: a region 32 km from Panna. There were 4 ratings given to the Panna diamonds:
1. Motichul: pure and vibrant
2. Manik: light orange nuance
3. Panna: green nuance
4. Bunsput: sepia nuance
The Diavik Diamond Mine is a Canadian mine, about 300 kilometers north of Yellowknife. It is an important part of the regional economy with a gross profit of approximately 100 million dollar. There is about 8 million ct or 1.600 kg diamonds cultivated annually. The area was prospected in 1992 and the mining began in 2003. The lifespan of the mine is estimated between 16 and 22 years. The mine consists of 3 Kimberlite pipes. It is an inhospitable area. In 2006 the road from Yellowknife to the Diavik mine froze early and thawed late, so the trucks couldn’t move the goods in a timely manner. There was need for a new arrangement. In 2007, a consortium of 7 mining companies met to conduct a study of the costs and benefits for building a deep-sea port. The plans include the creation of a 211 km long road that connects the port with the mines. This would facilitate the transport of diamonds.
The crater of the Park of the State of Diamonds in Arkansas is the only place in the world, where diamonds are mined, and which is open to the public. The Park is 3.69 km ². The park is open to the public and, for a small fee, visitors can look for diamonds. The visitors of the park find over 600 diamonds each year. The visitors can keep any gemstone regardless of its value. In 1924 a 40.23 carat diamond was found, this was the largest diamond ever discovered in North America. The crater itself is a plowed field of 142.000 m². It’s periodically plowed to bring the diamonds and other gemstones to the surface.
The Merlin diamond mine is one of only three diamond mines in Australia. The mine is located in the northern territory of Australia, about 80 km south of Borroloola. The mine was in operation from 2000 till 2003. In this period approximately 500.000 ct diamonds of excellent quality were cultivated. The Merlin mine had an unusual high part of gem quality diamonds: 65% of production is gem quality, and only 35% is classified as industrial quality.