Democratic Sentinel, Volume 20, Number 30, Rensselaer, Jasper County, 31 July 1896 — Mica. [ARTICLE]

Mica.

The commercial micas are: Muscovite (white mica), phlogopite (amber mica), biotite (black mica;. Muscovite is used principally for stove panels. For this purpose it must be clear and free from spots. The best muscovite is ruby red in color when in blocks. The white coloi comes next in value. The sizes of the sheets most desired for commercial purposes are x 2 inches up to 8x 10 inches. Phlogopite is u-ed chiefly sot electrical purposes, and is free from wrinkles < r crevices. It splits easily and is very flexible, stands a very high temperature without disintegrating, dark spots lessen its value. Waste mica is ground and used as a lubricant for heavy bearings, in certain insulating compounds, for decorating wallpipers, and as a' fertilizer. Scrap mica is made up into large sheets by a patent process. The principal sources of mica are India, Canada and the United States. Machinery is liable to injure the sheets. Mica is mined chiefly by hand. The mineral is blasted, sorted, split to the correct thickness, and then trimmed and packed for the market in packages of one pound. As a rule only 4 per cent is brought into a marketable form, so that the waste is enormous.