Alabaster, a name (said to be of Arabic origin and to signify "white stone") properly restricted to the translucent or semi-opaque massive varieties of gypsum or hydrous calcium sulphate. When pure it is white, with a pearly lustre. A. yellow variety known as "alabastra agatato" occurs at Siena. The mineral is not uncommonly fibrous in texture, and is then silky in lustre, and is called "satin-spar." Being very soft, capable in fact of being scratched with the finger-nail, it is readily carved or turned into statuettes, vases, and other ornamental articles. It is not uncommon, occurring in thick beds with the more earthy variety of gypsum, which is quarried for the manufacture of plaster of Paris. Derbyshire and Staffordshire are the chief counties in England in which it is worked. Florence has long been the centre of the alabaster trade of the world, the mineral being abundant in Tuscany, and at the time of the Renaissance it became a favourite material for tombs and other sculpture. Being slightly soluble it is not suited for out-door use, and though its softness makes it comparatively cheap, it is hardly durable enough for work of permanent value. The name "Oriental alabaster," "Algerian onyx," or, "onyx marble," is applied to a stalagmitic variety of calcium-carbonate, a slightly harder and entirely distinct substance, generally clouded in concentric curves with shades of brown, and long quarried in Oran, Algeria.