Mine Closure - Mining and the Environment: From Ore to Metal - page 798

21

Mine Closure

It is Not Over When It is Over

CARBON

Carbon, a non-metal, is the fourth most abundant element, and occurs as three distinct
allotropes: amorphous carbon (as found in charcoal), graphite and diamond. The
contrast is extreme with graphite, black in colour, among the softest substances while
diamond, colourless, is the hardest. Carbon provides the chemical basis for life on Earth,
forming more than 10 million known compounds, more than any other element. Coal,
the predominant fuel of the industrial revolution and still the major fuel for power
generation, is a major source of carbon as are the hydrocarbons - natural gas and
petroleum. However, most of the carbon in the Earth's crust occurs as carbonates in
limestone, dolomite and magnesite deposits, which are predominantly biological in
origin. Less than 1% of the world's carbon occurs in the biosphere, with the atmosphere
accounting for a very much smaller fraction. The carbon cycle within the biosphere is
complex and imperfectly understood. Diamonds, because of their unique physical
properties, have numerous industrial uses. However, their main value is as precious
stones, used in jewellery.