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242 61’PSUM FAMILY. «r even selenite, ns one of its ingredients. Its most im portant use is in the preparation of slucco: for this pur pose, the gypsum is first exposed to a heat sufficient to drive off its water of crystallization, then finely ground, mixed with a small portion of fine sand and quicklime, and, lastly, a determinate proportion of water is added, which occasions the compound first to swell, and then to contract and harden. Stucco is sometimes used for lining walls and roofs of apartments, in place of common plas ter ; and occasionally for covering the floors of summer houses or churches. The finest kind of stucco is used for casts of figures, and statues of various kinds. Ar tificial coloured marbles are also made of stucco, which are used for covering pillars, walls, altars, pavements of churches, or halls. Fifth Subspecies. Sparry Gypsum or Selenite. Fraueneis, IFcrncr. Gypsum selenites, Wall. t. i. p. 165.—Selenite, Romd de I.isle, Li. p. 441.—Fraueneis, Wern. Cronst. s. 53.—Broad foliated Gypsum, Kirw. vol. i. p. 123 Fraueneis, Emm. b. i. s. 640. —Chaux sulphatee cristallisee, Ilauy, t. ii. p. 266.—La Se lenite, Broch. t. i. p. (iop.—Spn'higer Gyps, Beuss, b. ii. 2* s. 406.—Fraueneis, Lud. b. i. s. 164. Id. Suck, lr tli. s. 67^ Grossblattriger Gyps, Bert. s. 10.9.—Fraueneis, M°h s > b. ii. s. 183. Id. Ilab. s. 84.—Spathiger Gyps, Lconhafdr Tabel. s. 37.—Chaux sulphatee Selenite, Brong. t. i. p. 17 1, —Spathiger Gyps, Karslen, Tabel. s. 52. Id. Ilaus, s. 12*' —Selenite, Kid, vol. i- p. 66.—Gyps-spath, Lews. b. ii. s. 840- —Durchschtiger Gyps, Okeu, b. i. s. 400. External Characters. Its colours arc greyish and yellowish white: ft' 0 ’ 11 yellowish'
