In alkali granites, arfvedsonite is a common constituent, as are other sodic-amphiboles and pyroxenes. The mineral, which was first discovered in Greenland and is named for Swedish chemist Johan Arfvedson, is an iron-rich sodium silicate. It is dark green or black in color and has a relative hardness of 6. Deposits of alkali granite can be found in various locales, such as New England and Norway, but are most extensive in Nigeria.