USES OF By far the most important of the uses to NvItich minerals are put is that of producing metals from those of them which con tain metal censtittienis iu sollieient quantity to render their mining profitable. The disenssion of the distribution and mode of occurrence of metallic ores involves many questions of a purely technical nature and belongs essentially to the province of or' deposits (q.v.). .\ few metals such as gold. platinum, copper. arsenic. and to sonic extent silver. antimony. bismuth, and mer eury are found native, that is, uncombined with other elements. The majority of the metallic ores. however, occur as sulphides, oxides. or ear Imitates of the various metals, or more rarely as arsenides. tellurides. chlorides, or silicates. Asso ciation of metallic minerals in more or less inti mate mixtures often gives rise to highly complex ores. Many ores which are essentially emit pound,: of the base metals contain gold and silver in appreciable aminnits and are profitably mined for the latter metals, as is the case with the argentiferous galena of ('olo•ado, Montana, and Utah.
The uum•mctatlie minerals, although of less importance commercially than the metallic ores, are none the less of great and inereasing value in the arts. 'Flues' are grouped. with referetwe to
their application, into: ( I) Stile:lamps used for chemical enthraeing the minerals em ployed in the thanufaciare of acids, soda, alma, plaster of Paris. ete. (2) Ceramic materials used in making pottery, bricks, tiling. paving blocks. terra.colla. porcelain. and glass. (3) nnafg rials, used in the manu facture of fire-proofing, linings of furnaces, cruel Ides. and asbestos fabrics, (4) Abrasives, em bracing diamonds. emery, garnet, and quartz sand. (.3) Graphic materials, embracing, chalk, graphite. pencil stone, lithographic limestone, etc. (6) Pigments, including inimrals ground for paints, and paint adulterants. (7) Fer tilizers, represented by the lime phosphates marls, and land plaster. (8) :Mineral fuels, in , cluding coal. petroleum, and natural gas. The use of certain minerals for gems is probably of very ancient. origin. The extreme hardness of the diamond, sapphire. ruby, emerald, chrysoberyl, and other precious stones protects them from injury and renders them capable of being highly polished.