THE NONMETALLIC MINERALS. 



173 



fact lire of pencils or crucibles. The average formula of the mixture 

 is: Graphite, 80 parts; steatite, soapstone, or talc, 14 parts; alum, 6 

 parts; but this varies with the purpose to which the material is to be 

 applied. When several different kinds of graphite have to be employed, 

 the richest in carbon is first mixed into the alum solution. By this 

 process graphites previously regarded as incapable of being compacted 

 are utilized, and are improved in polishing power. For pencils the 

 material may be hard without being brittle, and black without being 

 soft, while crucibles made from the treated graphite are at once harder, 

 more durable, and lighter. 1 



Prices. The value of the mineral varies with its quality. In 1899 

 the crude lump was reported as worth $8 a ton and the pulverized $30. 



The annual output as given 2 for the principal countries is as follows: 



World 's production of graphite. 



a Not reported in the Government statistics. 



BIBLIOGRAPHY. 



b Exports. 



J. W. DAWSON. On the Graphite of the Laurentian of Canada. 



Quarterly Journal Geological Society of London, XXVI, 1870, p. 112. 

 M. BONNEFOY. M^moire sur la Geologie et 1' Exploitation des Gites de Graphite de 

 la Boheme Meridionale. 



Annales des Mines. 7th Ser., XV. 1879, p. 157. 

 JOHN S. NEWBERRY. The Origin of Graphite. 



School of Mines Quarterly, VIII, 1887, p. 334. 

 Der Graphitbergbau auf Ceylon. 



Berg- und Huttenmannische Zeitung, XLVII, 1888, p. 322. 

 J. WALTHER. Ueber Graphitgange in zersetztem Gneiss (Laterit) von Ceylon. 



Zeitschrift der Deutschen Geologischen Gesellschaft, XLI, 1889, p. 359. 

 A. PALLAUSCH. Die Graphitbergbaue im siidlichen Bohmen. 



Berg- und Huttenmiinnisches Jahrbuch, XXXVII, p. 95, 1889. 

 T. ANDREE. Graphite Mining in Austria and Bavaria. (Abstract.) . 



Journal of the Iron and Steel Institute, 1890, p. 738. 



1 Engineering and Mining Journal, LVI1I, 1894, p. 440. 

 3 The Mineral Industry, VI, 1897; VIII, 1899. 



