What forms a diamond?

Answer 1

Diamonds are formed as an allotrope of the element carbon, at depths greater than 90 miles. The pressure and heat at this depth is critical to the formation of the diamonds that are mined at the surface today. At crustal pressures, the stable form of carbon is the allotrope graphite. Diamond was transported to the surface by supersonic volcanic eruptions that carried molten rock material from the mantle that contained diamond and other mantle minerals. Diamond is not formed from metamorphosed coal, and most diamonds discovered on the surface in mining operations are at least one billion years old; some may be two or three times that age. Diamond can also be formed from the pressures of high speed impacts of meteors with the Earth, but these are more of scientific interest, having no economic usefulness due to their small size and dispersion.

Answer 2

Just take some carbon. eg burnt toast.

Apply 450,000 Kg (1 million lbs.) per square inch and heat it to 1,650 C (3000 F).

There, you have your diamond.

For how they form in nature,

Diamonds form deep within the upper mantle, Earth's crust, in narrow volcanic chimneys called Kimblerlite pipes. Intense heat and pressure from all sides cause diamond crystals to form from the element carbon.

Geologists belive magma explodes up through the kimberlite pipes with shattering force. as it shoots its way through the crust to the surface, the magma carries the diamonds with it.

Kimberlite pipes are first mined where they reach the surface. Once rock has been dug down to about 312 m(1000 ft), danger from cavings forces miners to change tactics. They dig a deep shaft parreral to the Kimberlite, then cut tunnels across to the pipe. Blasted loose, blue kimberlite rock is carried to the surface and sifted for diamonds.

Answer 3

Diamonds are formed as an allotrope of the element carbon, at depths greater than 90 miles. The pressure and heat at this depth is critical to the formation of the diamonds that are mined at the surface today. At crustal pressures, the stable form of carbon is the allotrope graphite. Diamond was transported to the surface by supersonic volcanic eruptions that carried molten rock material from the mantle that contained diamond and other mantle minerals. Diamond is not formed from metamorphosed coal, and most diamonds discovered on the surface in mining operations are at least one billion years old; some may be two or three times that age.

Diamond can also be formed from the pressures of high speed impacts of meteors with the Earth, but these are more of scientific interest, having no economic usefulness due to their small size and dispersion.

Answer 4

Most geologists believe that diamonds form in Earth's mantle from inorganic carbon under intense high heat and enormous pressure over eons of time.

Answer 5

Diamonds are formed from carbon. Once formed as diamonds, there is no further formation.

Answer 6

This geological phenomenon takes place in cratons in the lithospheric mantle of the earth.

You can read more about it in detail, below.

Answer 7

Stones.....