Carbon the very large masses of carbonate rock (limestone, dolomite, marble and so on). Coal is very rich in carbon (anthracite contains 92–98%) and is the largest commercial source of mineral carbon, accounting for 4,000 gigatonnes or 80% of fossil fuel. As for individual carbon allotropes, graphite is found in large quantities in the United States (mostly in New York and Texas), Russia, Mexico, Greenland, and India. Natural diamonds occur in the rock kimberlite, found in ancient volcanic "necks", or "pipes". Most diamond deposits are in Africa, notably in South Africa, Namibia, Botswana, the Republic of the Congo, and Sierra Leone.
Coal power in the United States and put pressure on older plants. In 2007, 59 proposed coal plants were cancelled, abandoned, or placed on hold by sponsors as a result of financing obstacles, regulatory decisions, judicial rulings, and new global warming legislation. The Stop Coal campaign has called for a moratorium on the construction of any new coal plants and for the phase out of all existing plants, citing concern for global warming. Others have called for a carbon tax and a requirement of carbon sequestration for all coal power plants. The creation in January 2009 of a Presidential task force (to look at ways to