GRAPHITE 307 



in grayisli black schist, have been exploited for a lenp;th of 

 over 600 feet. The preparation for market consists in simple 

 screening. The product, which contains nearly 80 per 

 cent of carbon, is used in making graphite crucibles. 



Other graphite deposits arc found in lower Austria, Mora- 

 via, and Carinthia; but the mineral, which is associated with 

 granular limestone in gneiss, and is usually amorphous and 

 friable, is too impure to warrant working commercially. 



The graphite deposits of Germany are confined to the 

 easternmost corner of Bavaria. In a region bounded on the south 

 by the Danube and on the east by the Austrian frontier are 

 gneisses and gneissose rocks impregnated with scaly graphite. 

 In some places — chiefly in the immediate neighborhood of 

 intercalations of granular limestone, altered by contact met- 

 amorphism — the mineral occurs in lenticular masses, rich in 

 carbon. Both the graphite-bearing rock and its near neighbors 

 are highly decomposed, so that kaolin and other decomposition 

 products are found in intimate association with the graphite 

 deposits. The lenticular form of the deposits, their geological 

 relationship with limestone intercalations, and their frequent 

 association with kaolin and other decomposition products 

 connect them closely with the Bohemian type, from which they 

 are differentiated by the less compact and more crystalline 

 character of the graphite. The genetic connection between 

 the Passau and Ceylon tj^es is very close. 



At Borrowdale, England, fine-scale graphite was at one 

 time found in veins in greenstone porphyry. The gangue 

 material was chiefly calc-spar, brownspar, and quartz, con- 

 taining nests and lumps of very fine graphite, especially suit- 

 able for the manufacture of pencils. These mines, however, 

 have been exhausted. 



The mines at Batugol, province of Irkutsk, Siberia, also 

 are practically exhausted. The graphite was finely fibrous 

 and purer than that at Borrowdale. The veins run tlirough a 

 granite or dioritic rock, while in the closely adjoining limestone 

 (altered by contact metamorphism) are great lumps of pure 

 graphite, suitable only for pencils. 



Graphite can be made artificially in several ways, among 

 which are the following : 



