Gold Diamonds Loose

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What is Diamond?

Diamond is a colourless exceptionally hard mineral (but often tinted yellow, orange, blue, brown, or black by impurities), found in certain igneous rocks esp. the kimberlites of South Africa. It is used as a gemstone, as an abrasive, and on the working edges of cutting tools. Composition: carbon. Formula: C. Crystal structure: cubic. Name derived from the Greek adamas meaning invincible. Relative density 3.50- 3.52. Cleavage eminent along octahedral faces. Fracture conchoidal. Tenacity brittle. Lustre brilliantly adamantine. Refractive index 2.417- 2.419. Birefringence and pleochroism: none (cubic). Dispersion strong 0.044. Diamond crystals form as cubes, octahedra , the most common gem form, and dodecahedra. Colourless to yellow diamonds which have a strong absorbtion line in the violet end of the spectrum are members of the Cape series.

Where is it found?

The most famous diamond bearing country is South Africa. The first diamond was reported in 1866. By 1869 an 83.5 carat diamond had been found and was named The Star of Africa. It was subsequently cut into a pear shape brilliant weighing 47.74 carats. The Golconda area of Southern India has been the source of some Argyle Mine North Western Australiafamous diamonds such as the Koh-i-nor (mountain of light 186cts cut to 108.92 cts and now in the Tower of London) and Jehangir. Diamond is widespread in Brazil, most stones being small but of good gem quality. Alluvial diamonds have been found in most states of the USA. White and fancy coloured diamonds such as pinks and pinkish browns are mined at Argyle in North Western Australia. Other important producers are Russia, now the fourth largest producer, and China.



  By weight the top ten producers in 1994 were:   By Value The top ten were:
  Australia   Botswana
  Zaire   Russia
  Botswana   South Africa
  Russia   Zaire
  South Africa   Australia
  South America   Namibia
  Angola   Angola
  Namibia   South America
  Ghana   Guinea
  Guinea   Sierra Leone
       

Estimated 2001 Diamond Production by Country  
Country Carats
(000)
Value
($ m)
Botswana 26,416 2,194
Russia 20,500 1,650
South Africa 11,301 1,145
Angola 5,871 803
D.R. Congo 19,637 496
Canada 3,685 531
Namibia 1,502 322
Australia 26,070 294
Guinea 754 128
Sierra Leone 375 68
Central Africa Republic 614 92
Venezuela 325 41
Tanzania 191 28
Brazil 550 22
Liberia 155 23
Ivory Coast 145 17
China 150 15
Ghana 450 11
Lesotho 20 4
Guyana 20 2

Total
110,176 7,253
*Source: Mining Journal, London, August 23, 2002
 

Current Annual Production at World's Major Mines, 2001

Country

Carats Tonnes US$/carat Value
(000) (000) ($ m)

Canada

Ekati 3,685 3,685 144 531

Botswana

Jwaneng 12,339 8,920 110 1,357
Orapa 13,056 15,779 50 653
Letlhakane 1,021 3,625 180 184

South Africa

Venetia 4,977 4,602 85 423
Namaqualand 808 6,083 180 145
Finsch 2,465 4,768 70 173
Premier 1,637 3,102 75 123
Kimberley 550 3,766 110 61
Baken 65 5,835 400 26
Koffiefontein 145 2,299 225 33

Russia

Udachnaya 11,500 9,000 85 978
Jubilee 5,500 9,100 65 358

Australia

Argyle 26,000 15,100 11 286
Merlin 70 270 110 8

Namibia

Namdeb Onshore 1,385 21,867 220 305

**Source: Mining Journal, London, August 23, 2002


How diamonds are formed?

Diamond genesis, final eruption stage of kimberlite volcano.Diamond is formed at great depth in the earth, between 150 and 300 km below the surface and at great temperatures and pressures. By a kind of volcanic eruption the diamonds were pushed up through volcanic pipes of diamond bearing rock such as kimberlite. With gradual erosion kimberlite chimneys were exposed at the earths surface.