( ^^ ) 



the accessory minerals have more often been able to crystallize in 

 their own forms ; for an example see Fig. 1, an octahedral crystal 

 of spinel. Such " idiomorphic" crj-stals are commonly known 

 in Ceylon as " devil-cut." 



It is interesting to note that of all the gem minerals so famous 

 in Ceylon few have yet been found in situ. New records of the 

 occurrence of these minerals in their parent rock is much desired. 

 Nearly all the gems of Ceylon, moonstone excepted, are obtained 

 from the river gravels of the Ratnapura, Rakwana, Galle, and 

 Morawak Korale Districts ; but some are found in superficial 

 deposits whose situation on hill slopes shows that the contained 

 minerals must occur in situ at no very distant spot. 



Fig 1. — Octahedral crystal of spinel. 



Minerals of the second class include the greater part of the 

 graphite of Ceylon and perhaps a considerable part of the mica. 

 Associated with the graphite are often found some of the minerals 

 characteristic of the granulites, such as quartz and felspar. True 

 veins of pure quartz are rarely met with in Ceylon. Minerals of 

 the third class include the deposits of iron ore (limonite) and 

 manganese ore (psilomelane), which are everywhere common as 

 decomposition products of the granulites ; and also the minerals 

 hydrargillite and limonite composing laterite. 



A few minerals occur in Ceylon which have not been found 

 elsewhere; these are thorianite, geikielite, and serendibite. The 

 mineral baddeleyite was first found in Ceylon, but has since been 

 met with in Brazil. 



Further notes on the more important minerals will be found 

 below, where a list of all the minerals known to occur in Ceylon 

 is given. 



Graphite, C. — Graphite or plumbago is the most important 

 mineral product of Ceylon. Its composition is pure carbon. It is 

 found in veins and nests in the crystalline rocks, occurring often 



