Diamonds Flashcards
graphite to diamonds
crystallised to form octahedral
two uses of diamonds in industry
mining
or cutting and polishing for jewellery
carat = 0.2 grams worth?
$1000s
1997 production worth?
US$7Bn
2008 production worth?
US$9Bn
Diamond producing countries
S Africa
Botswana
diamond importing
EU, India
average diamond price is?
declining
De Beers 4 Cs
Carat Colour Clarity Cut = COST
diamonds produced in ? countries
21
Gem producers
RSA, Namibia, Botswana, Russia
Industrial producers
Australia, Botswana, DRC
Central Selling Organisation (CSO) - De Beers
to maintain price (high) and stability (rhodes). Includes 80% of global trade
stockpiling
$2-5Bn
1949-1990 price of diamonds ^
1800%
geochemistry of kimberlites
Ultramafic MgO >12/15% Ultrapotassic REE enrichment LILE enrichment High CO2 and H2O Primitve Ni, Cr, Co
Kimberlite pipe
2km deep, magma ascends 70km/h,
highest grade on crater rim
82 degree slope
xenocrysts
a crystal in an igneous rock which is not derived from the original magma.
diamond bearing kimberlites found in
thick continental crust of archean age
presence of diamonds in kimberlites
30%, 1% mineable
origin of kimberlites
depths below 150km, rapid ascent to avoid conversion to graphite, presence of coesite suggests depth
