237 



COLLECTION OF MINERALS. 

 CARBON. 



666. GRAPHITE. (Plumbago, Blacklead.) 



a. Foliated. Two specimens. 



Note. Graphite often contains traces of silicum, aluminium, iron, 

 magnesium, and calcium. See Dana, Mineralogy, 5th. ed., p. 24. Known 

 from molybdena by its deflagrating on heated charcoal. 



FLUORINE. 



667. FLUOR SPAR. Ca F. (Fluorite, Derbyshire Spar.) 



a. Amethyst variety, from Derbyshire. (Blus John.) 



b. Green variety, from Cornwall. (Chlorophane.) 



Note. Used for the production of hydrofluoric acid. See Dana, Mine- 

 ralogy, p. 124, for fig. of crystal, etc. 



SULPHUR. 



668. NATIVE SULPHUR. 



a. Massive, from Dominica. 



TELLURIUM. 



669. FOLIATED TELLURIUM. (Magyagite, Black Tellurium.) 



a. Three small specimens, from Transylvania. 

 Note. This mineral has somewhat the appearance of some varieties of 

 galena, but differs in being softer, so that it is easily cut by a knife into 

 thin flexible lamin ; and it gives a greyish sublimate when heated in 

 contact with air. This mineral consists chiefly of tellurium (15 to 30 per 

 cent.) and lead, with small quantities of sulphur and lead and traces of 

 silver and copper. See Dana, Mineralogy, p. 83. 



BORON. 



670. TINCAL. (Native Borate of Soda.) 



a. In small crystals, from Thibet. 



b. A very large crystal with rounded angles. 



c. Massive, from Nevada. 



671. BECHILITE. (Hydrous Borate of Lime.) 



a. Massive, probably from Asia Minor. 



Note. This specimen is almost pure borate of calcium, and has the 

 appearance of white marble. 



672. HAYESCINE. (Ulexite, Borocalcite, Hydro-borocalcite.) 



a. In rounded nodules, from Iquique in Peru. 



jfote. This mineral consists almost entirely of the boratesof calcium 

 and sodium. The nodules, which are rather dirty externally, are formed 

 of agglomerated snow-white, soft, acicnlar crystals. Yellowish prismatic 

 crystals of glauberite (a double sulphate of sodium and calcium) are fre- 

 quently found inside the nodules. See Dana, Mineralogy, p. 592. 



