ALABASTER, in present-day usage refers to a very fine grained and compact, snow-white or light-colored, massive variety of gypsum (hydrated calcium sulphate) which is used for interior ornamental work. Alabaster of the ancients, or oriental alabaster (including Algerian onyx), was marble. It was used for making ointment jars (Matt 26:7; Mark 14:3) and the Algerian onyx was used in buildings of Carthage and Rome. The marble is generally banded with the so-called onyx-marbles consisting of concentric zones of calcite or aragonite (both calcium carbonate). When pure it is white or translucent. Impurities give a great variety of colors, particularly cream, yellow, buff, brown and red due to the presence of iron oxide. Strictly speaking it is neither marble nor onyx, for the onyx is a banded chalcedony (q.v.) composed largely of silicon dioxide.