240 



087. GYPSUM. (Sulphate of Lime.') 



a. A large crystal, from Shotover Hill, Oxfordshire. 



Note. For other specimens see the case, No. 9, containing crystalline 

 forms. For a fig. of crystal, see Dana, Mineralogy, p. 637, fig. 535. 



b. Satin Spar. 



c. Fibrous Gypsum. 



d. Alabaster. (Plaster Stone.) 



Note. The name Satin Spar is also applied to fibrous carbonate of lime, 

 which has a pearly lustre like that of specimen b. It may easily be dis- 

 tinguished from gypsum by effervescence with acids. See Dana, Mine- 

 ralogy, p. 638. 



ALUMINUM. 



688. BAUXITE. (Beauxite.) 



a. Massive, of a reddish tint. Two specimens. 



Note. This mineral consists of the hydrates of aluminum and iron. 

 See Dana, Mineralogy, p. 176. 



689. CRYOLITE. 



a. In translucent masses, from Greenland. 

 Note. Cryolite is a double fluoride of sodium and aluminum. Both 

 these minerals and Bauxite, are used as sources of aluminum. See Dana, 

 Mineralogy, p. 126. 



690. WAVELLITE. (Devonite, Subphosphate of Alumina.) 



a. In greenish globular concretions, having a radiated 



structure, from Barn staple. 

 Note. For description, etc., see Dana, Mineralogy, p. 576. 



691. GIBBSITE. (Hydrate of Alumina.) 



a. Massive. 

 Note. See Dana, Mineralogy, p. 177. 



692. ALUM SHALE. 



a. From Whitby. 



fc. Fossils from the lower strata. 



c. Fossils from the middle strata. 



d. Fossils from the upper strata. 



GLUCINUM, OR BERYLLIUM. 



693. BERYL. 



a. Four specimens of a pale green hue. 



Note. Beryl is a silicate of aluminum and glucinum with traces of 

 iron, to which the greenish colour of some specimens is due. 



CERIUM. 



694. CERITE. 



a. Massive, tinged here and there of a peach colour. 

 Note. This mineral is a silicate of cerium, lanthaninm, and didymium, 

 and small quantities of those of iron and calcium. See Dana, Mineralogy, 

 p. 413. 



