Natural diamonds were formed about 2000 to 4000 million years ago at a depth 150 to 300 km within the Earth's crust. Under immense pressure and temperatures of 900 to 1300C, carbon atoms combined to crystallize and grow as diamonds within rocks called peridotite and eclogite. Molten magma forced up by similar pressures, were forced up through diamond bearing rock. It partly melted the peridotites and eclogites, capturing the diamonds and carrying them to the surface through deep and narrow fissures. Nearer to the Earth's surface, the magma encountered ground water resulting from a series of violent explosions. Fragmented by explosions, the magma erupted at the Earth's surface to form a pipe, expelling ash which was rich in diamonds. Over millions of years the ash within the pipe solidified to become a diamond bearing rock called tuff. (Source: Australian Geographic, No 42, January to March, 1996)

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1. Depth



2. Forming of Diamonds

Forming of Diamonds

3. Volcanic Activity

Volcanic Activity

4. Today's Situation

Today's Situation