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are tilled with disseminated graphite ; the latter occurs only in 

 strings or scales occupying obvious cavities or cracks in the quartz. 

 It seems that the deposition of graphite has been subsequent to the 

 formation of the pegmatite veins, though following the same or 

 similar paths in some cases. 



As regards the source of the graphite, we see at once that its 

 presence cannot be ascribed to the metamorphism of beds of coal 

 or other carbonaceous deposits, and indeed that the graphite can 

 have had no direct organic source and is most probably of entirely 

 inorganic origin. Like other minerals found in veins, it must have 

 been deposited from vapours or liquids saturated with mineral 

 (in this case carboniferous) matter ; for we cannot suppose that 

 the graphite was introduced in the form of dykes of molten 

 carbon. 



Snlphur, S. — Occurs as a decomposition product of pyrite in 

 small quantities. 



Gold, Au. — Small quantities of native gold are of rare occur- 

 rence in streams, sands, and alluvial deposits, but there is little 

 prospect of its ever becoming of commercial importance. 



Salt, NaCl. — Obtained by the evaporation of sea water in natural 

 and artificial lakes, known as " lewaya." 



Cinnabar, HgS. 



Pyrite, FeS.^. — Common as an accessory mineral in granulites 

 and crystalline limestones. 



Marcasite, FeSa- 



P///v/w^//(«, FenS,.,.— Occasionally as an accessory mineral in 

 crystalline limestones and in charnockite. 



Ice, HoO. — Frost is sometimes experienced in the hills. 



Fisr 8. — Coi-undum. 



Gornndum, AUO j. — Corundum is the most important of the gem 

 minerals of Ceylon. When red it is known as ruby ; when blue 

 as sapphire ; when purple as oriental amethyst ; when yellow as 

 oriental topaz ; i-olourless varieties ar(( also found. The peculiar 



