The New Student's Reference Work/Emery

Em′ery, a mineral belonging to the same class as ruby, sapphire and other precious stones. In outward appearance emery has nothing in common with the precious stones to which it is related. It is a dense, opaque, dull, bluish-black substance, like a fine-grained iron-ore. It is found in large, bowlder-like masses on Naxos and some of the other islands of the Grecian archipelago. It is made ready for use by first breaking it into lumps about the size of a hen's egg, then crushing these to powder by stampers. It is then sifted to various degrees of fineness. Emery-powder, as it is next in hardness to diamond-dust and crystalline corundum, is used for cutting and polishing many kinds of stone. Glass stoppers of all kinds are ground into their fittings with it. Plate-glass is ground flat by its means. When used for polishing metals, it has to be spread on some kind of surface to form a fine file. Emery-paper, emery-cloth, emery-sticks, emery-cake and emery-stone are used for this purpose. Emery-wheels are largely used for polishing iron-castings. They are a mixture of emery-powder and hard, vulcanized india-rubber.