Big Hole
The Big Hole ( German: The big hole ) of Kimberley in South Africa is the opencast mine of the former Kimberley Mine, were promoted from the to 1914 diamonds.
The hole is often referred to as the "biggest ever dug by man hole". The Big Hole competes for this record status with Jagersfontein, an open pit 110 km south-west of Bloemfontein. The Big Hole is a little deeper, Jagersfontein, but features a larger volume. The term is misleading, however, since both opencast mines are very small compared to the largest open pit in the world at Chuquicamata; it applies only when limited to rather simple tools, dynamite and vertically dug into the depths convex cavities.
Geology
The diamond- bearing rock is a brekzienartiges subvulkanisches material fragments of peridotite, Granatperidodite, Granatpyroxenite and eclogites from the lower crust and upper mantle carries. After the South African city came to great prominence this type is called kimberlite rock. It involves serpentinisierte and carbonated Glimmerperidotite. One of the main minerals include olivine, phlogopite, diopside, serpentine and calcite. The diamonds are present as phenocrysts.
Data
The Big Hole has a surface of 17 hectares, it has. At the surface a circumference of 1.6 km and a diameter of 460 m From 1871 until the cessation of mining in 1914 22.5 million tons of soil were excavated. The period in the same amount of diamonds was brought to light 2722 kilograms or 14.5 million carats.
When setting the open pit mining operation, the hole was 240 m deep. Today it is partly filled with groundwater; the water level is now 175 m below the surface. The underground mining reached a depth of 1097 m.
The Big Hole is located in the city and is well worth seeing on the one hand because of the huge dimensions, and secondly because of the mining and open-air museum on the edge of the Big Hole. In addition, between the town hall and the Museum runs a historic tram. Today, the original form of the volcanic chimney as erosion of diamond extraction is clearly visible.
History
Once in 1866, a first diamond ( "Eureka", 21.25 carats) near the Oranje and more diamonds on the open field in Alluvialsedimenten had been found, the trader John O'Reilly made by Dr. Anthestone at Rhodes University of analyze Grahamstown samples which he identified as diamonds. Worked around 50,000 people on the diamond fields around Kimberley in 1870. The brothers Johannes Nicolaas and Diederik Arnoldus de Beer bought in 1871, arable land in South Africa, but could the pressure of the growing diamond market do not stand up and sold the mines. Nevertheless, a mine took her name. In July 1871 Fleetwood Rawstorne discovered a handful of diamonds in Colesberg Kopje, which later became the Big Hole.
1888, the organization " De Beers Consolidated Diamond Mines " by Cecil John Rhodes and Charles Rudd was launched. On August 14, 1914 The Big Hole was closed due to lack of profitability.
The De Beers Company now controls virtually the entire diamond market.
Tourism
From a steel frame from one can look into the abyss. There are guided tours around the Big Hole and a large museum where the history of the Big Hole is shown.