CHRYSOBERYL, a yellow or green gem-stone, remarkable for its hardness, being exceeded in this respect only by the dia mond and corundum. The name suggests that it was formerly regarded as a golden variety of beryl. Its composition is BeA1,04, or It is yellow or pale green, occasionally passing into shades of dark green and brown. Chrysoberyl is often mistaken by its colour for chrysolite (q.v.), and has indeed been termed oriental chrysolite, but it is a much harder and denser mineral. As the two stones are apt to be confounded, it may be convenient to contrast their chief characters: Chrysoberyl is not infrequently cloudy, opalescent and chatoy ant, and is then known as "cymophane" (Gr. rw/sa, cloud). The cloudiness is referable to the presence of multitudes of micro scopic cavities. Some of the cymophane, when cut with a convex surface, forms the most valuable kind of cat's-eye (see CAT'S-EYE). A remarkable dichroic variety of chrysoberyl is known as alexandrite (q.v.).
Most chrysoberyl comes from Brazil, chiefly from the district of Minas Novas in the State of Minas Geraes, where it occurs as small water-worn pebbles. The cymophane is mostly from the gem-gravels of Ceylon. Chrysoberyl is known as a constituent of certain kinds of granite, pegmatite and gneiss. In the United States it occurs at Haddam, Conn. ; Greenfield Centre, near Sara toga Springs, N.Y.; Greenwood, Me. and in Manhattan island. It is known also in the province of Quebec, Canada, and has been found near Gwelo in Rhodesia.