The mineral charoite is a hydrated potassium-calcium silicate with the chemical formula (K, Na) 5 (Ca, Ba, Sr) 8Si6O15Si6O16 (OH, F) · H2O. It belongs to the inosilicates. The light brown, lilac or purple charoite has a glass to pearl luster, a white stripe color and good cleavage according to unknown crystal planes. The average density is 2.56 and the hardness is 5 to 6. The crystal system is monoclinic and the radioactivity of the mineral is barely measurable. The gamma ray value according to the American Petroleum Institute is 154.18. The name of the mineral charoite is derived from the Chara River in Siberia. The mineral charoite occurs in a syenite massif where limestone has been converted by contact metamorphosis of approximately 200 - 250 degrees Celsius. The typical location is the Murun massif, Chara river area, Aldan Shield, southwestern Sakha Republic. Charoite occurs here together with dark green aegirine needles, yellow tenakite and green white nepheline.