PART VII. CHAPTER I. ALABASTER. Gypsum, Gyps [Germ.) Chaux sulfatde (Fr.) Spec. gray. 2.28-2.4. Hardness, 1.5-2. Gypsum is a hydrous sulphate of lime, consisting in a pure state, of lime, 32.56, sulphuric acid, 46.51, water, 20.93. The name is derived from the Greek yv'l'ot, by which it was known to the ancients, who obtained their supplies chiefly from Cyprus, Phoenicia, and Syria, and applied the material to similar pur poses as the moderns. 1 In its crystalline form it occurs as selenite, which is translucent and colourless, limpid or white; or as satin spar, or fibrous gypsum, also colourless, and from its peculiar structure, in- 1 Bristow, Glos. Min. p. 167. Theophrastus, a Greek writer, who lived about 238 years b.c., in his work, History of Stones (‘ n f pi Ai0w'), of which there is an English version by Mr. John Hill (edit. 1774); gives a good account of the occurrence and use of gypsum and alabaster, cxii. to cxvi.