Carbon (C), nonmetallic chemical element in Group 14 (IVa) of the periodic table. Although widely distributed in nature, carbon is not particularly plentiful—it makes up only about 0.025 percent of Earth’s crust—yet it forms more compounds than all the other elements combined. In 1961 the isotope carbon-12 was selected to replace oxygen as the standard relative to which the atomic weights of all the other elements are measured. Carbon-14, which is radioactive, is the isotope used in radiocarbon dating and radiolabeling. Continue reading from Encyclopedia Britannica
Carbon occurs naturally as anthracite (a type of coal), graphite, and diamond. More readily available historically was soot or charcoal. Ultimately these various materials were recognised as forms of the same element. Not surprisingly, diamond posed the greatest difficulty of identification. Naturalist Giuseppe Averani and medic Cipriano Targioni of Florence were the first to discover that diamonds could be destroyed by heating. In 1694 they focussed sunlight on to a diamond using a large magnifying glass and the gem eventually disappeared. Pierre-Joseph Macquer and Godefroy de Villetaneuse repeated the experiment in 1771. Then, in 1796, the English chemist Smithson Tennant finally proved that diamond was just a form of carbon by showing that as it burned it formed only CO2. Continue reading from Royal Society of Chemistry
Carbon gets its name from the Latin word carbo, which means "coal." Diamond, the flashiest version of carbon, is formed under great pressure deep in the Earth's crust. The largest gem-quality diamond ever found was the Cullinan diamond, which was discovered in 1905, according to the Royal Collection Trust. The uncut diamond was 3,106.75 carats. The largest gem cut from the stone, at 530.2 carats, is one of the Crown Jewels of the United Kingdom and is known as the Great Star of Africa.
Diamonds and graphite are among the hardest and softest natural materials known, respectively. The only difference between the two is their crystal structure. The tattoos of Ötzi the Iceman, a 5,300-year-old corpse found frozen in the Alps, were inked from carbon, according to a 2009 study in the Journal of Archaeological Science. Small incisions in the skin were made, and charcoal rubbed in, perhaps as part of an acupuncture treatment. Continue reading from LiveScience
