- 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
 famous
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 |
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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
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-
How
diamonds are formed?
-
 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.
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