The word «kullblende» (coal blend) has been used during centuries at Kongsberg Silver Works as a designation for an anthracite-like «mineral». The workers there had a rule saying that where there is no coal blend or bituminous calcite there will be no native silver. In Sweden, where similar material occurs and is beeing thoroughly studied at present, it is called «berg bek» (mountain pitch), (Helland 1875, Hedström 1923). A more general designation, also used is «anthracite».