The New Student's Reference Work/Mica

Mi′ca, from a Latin word meaning to glitter, is a group of minerals which are noted as being easily divided into sheets. These sheets can be made so thin that it will take one thousand to make an inch in thickness. There are different varieties, what is called Muscovite mica being the most common form. It is formed largely of silica, alumina and potash, and is called a potash mica. It is found in granite rocks, in gneiss and in layers with quartz, making what is called mica schist. Large plates are sometimes found, as in New Hampshire, Sweden and Norway. Mines have been discovered in North Carolina. Mica is used in stoves and lanterns, because it is transparent and will bear heat. It is used in some countries for window-glass.