Till. N \TI\ I. ELEMENTS 'js:> 



:iii(l pre.-smv. It occurs in disseminated x-ales in crystalline | mi ,.. 

 stunes. as the Laurent ians of Canada. The graphite of ( 'olfax 



County, New Mexico, was formed \>\- contact of intruded i^ii' 

 rock with coal beds. Graphite occurs associated with diamond in 

 the ('anon Diablo meteor, and with native iron in the basalt of 

 < >\ifak, (Ireenland. A pegmatite of Maine contains 9 per cent. 

 of graphite, which lias separated from the magma after the feld- 

 spars and is contained as inclusions in the quartz. Graphite; con- 

 tained in fissures and veins at Ticonderoga suggests a pneumato- 

 lytic origin. 



Commercially most of the graphite mining in the United States 

 is carried on at Ticonderoga ; this is the crystalline form of graph- 

 ite and is used in the manufacture of crucibles, for the melting of 

 alloys and the refining of metals. The Ceylon product is consid- 

 ered better, being more fibrous, requiring less binder; at the present 

 time these mines supply most of the world's product. Graph- 

 ite has been used in pencils for several hundred years ; an amor- 

 phous product from Sonora, Mexico, is considered to be the best 

 for this purpose. A finely ground graphite is mixed with oil as a 

 lubricant. It is also used for electrodes in the electrochemical 

 industries, and the impure forms are used as a paint to protect iron- 

 work from rusting. 



Artificial. Fused metals dissolve carbon, iron as much as four 

 per cent., a large portion of which separates as graphite on cooling. 

 Thus cast iron contains carbon as graphite, which has been formed 

 under the same conditions as that contained in meteoric iron. It 

 is common in slags of blast furnaces. Graphite is produced at 

 Niagara Falls electrolytically, by the Acheson process, competing 

 commercially with the natural product. 



SULPHUR 



Sulphur. S; Orthorhombic ; Type, Dig<m;d Holoaxial; fi: 

 b : c = 0.8131 : 1 : 1.9034 ; 100 A 110 = 39 6', 001 A 101 = 66 

 52', 001 A Oil = 62 17', 111 A 001 =71 39'; Common forms, 

 c (001), P(lll),p (111), e (101), s (113), n (Oil) ; Twinning plane, 101; 

 ( 'leavage, c and m perfect, p imperfect ; Brittle ; Fracture, conchoi- 

 dal; H.= 1.5-2.5; G.= 2.05-2.09; Color, sulphur yellow and va- 

 rious shades of yellow ; Streak, white ; Luster, resinous ; Trans- 

 parent to translucent; a = 1.950, p = 2.038, y = 2.240; y - 

 a = .290; Optically (+); Plane of the optic axes = 010; 

 Bx a = c, 2 V = 69.5. 



