Geographic Minerals

Coltan (short for columbite–tantalites and known industrially as tantalite) is a dull black metallic ore from which the elements niobium and tantalum are extracted. The…

Clinochrysotile is a soft, fibrous silicate mineral in the serpentine group of phyllosilicates, also called “white asbestos”. It is a monoclinic form of Chrysotile. It…

Cleveite is an impure radioactive variety of uraninite containing uranium and found in Norway. It has the composition UO2 with about 10% of the uranium…

Citrine is a variety of quartz whose color ranges from a pale yellow to brown due to ferric impurities. It is a glassy yellow variety…

Chrysoprase is a gemstone variety of chalcedony that contains small quantities of nickel. It is an apple-green gemstone consisting of a variety of chalcedony that…

Chlorastrolite (also known as Isle Royale Greenstone), is a green or bluish green stone. It is named from Greek “chloros” – green, and “astros” –…

Chiastolite is a variety of the mineral andalusite with the chemical composition Al2SiO5. It is a form of the mineral andalusite containing carbonaceous inclusions giving…

Chalcedony is a translucent variety of quartz of various colors and waxy luster. It is a cryptocrystalline form of silica, composed of very fine intergrowths…

Ceylonite is dingy blue or grey with black varieties of spinel. It is a dark-colored spinel, called also pleonaste. It was named after the island…

Carnelian is a brownish-red mineral commonly used as a semi-precious gemstone. It is the red, orange, or an amber variety of Chalcedony. In ancient Egypt,…

Cementite is an intermetallic compound of iron and carbon, more precisely intermediate transition metal carbide with the formula Fe3C. It is iron carbide, a constituent…

Campylite is a variety of the lead arsenate mineral mimetite which received the name from the Greek ‘kampylos’- bent, on account of the barrel-shaped bend…