MISY, in natural history, a species of the chalciditha, a fossile very common in the Turkish dominions, and sometimes found in the mines of Cremona in Hungary. It is a considerably firm substance, of an irregular texture, not compact; much resembling some of our more gaudy marbles, but wanting in their hardness and weight. It is of no determinate shape or size; but is often found in small detached masses, which are usually broad, flat, and very rugged at the edges. As to its medical virtues, they are no other than those of the green vitriol.