Mica

Group of silicates of aluminium and pota ium with other bases, remarkable for their easy cleavage in one direction. The micas are common ingredients in many of the older crystalline rocks. When found in veins from which sheets of large size can be obtained, the mineral finds extensive use in the arts. The varieties of highest commercial importance are pota ium mica, muscovite, and magnesium mica, phlogopite. In the U. S. the principal mica mines are in N. H. and N. C. The fine refuse is used in lubricants, insulating compounds, and in the manufacture of wall-paper. The sheets are used in stoves and for electrical purposes. The U. S. produced, 1895, 740,000 lbs. ground mica and 6,200 lbs. sheet; the imports were 1,120,221 lbs.