208 Mineralogy of Southern India. 



mentioned by Dr. Heyne, as found near Hurryhur in Mysore. 

 Of its associations in India I do not know much, but I think 

 it belongs to the porphyritic or schistose series. 



Schorl felspar Porphyry. 



This is a rare rock, and I do not know much about it. I 

 have only met with it forming part of the mass of the Rya- 

 cottah rock, in the veins of hornblende felspar porphyry, 

 from which, like the last, it is easily distinguished by the 

 behaviour of the crystals of schorl before the blow-pipe 

 flame. It is composed of black schorl in saccharine fel- 

 spar. 



Schorl Rock. 



I believe I may put this down in the list of those I have 

 seen in Southern India ; but as I have not any specimens at 

 hand, I am unable to define its character, and as I cannot 

 find any record of the examination of them in my notes, I 

 must state what I recollect. The rock is found in mass in a 

 deep nullah at south-east end of the (Mallapanbetta Trap 

 dyke formation,) and almost exactly resembles black granite, 

 except perhaps in being a little more lead-coloured and more 

 brittle, and the structure of very minute aggregated crystals. 

 When properly examined, it might prove to be a " black 

 schorlaceous granite." I have never seen it in any other 

 locality, and in consequence I suppose the specimens have 

 been forgotten, among other pursuits. 



Clay -stone. 



Not common in Southern India, but occurs occasionally 

 among the porphyritic series, and sometimes associated with 

 white quartz ; and it graduates into wacke. Fracture : dull 

 and earthy, or imperfectly granular, or imperfectly conchoi- 

 dal, or imperfectly splintery. Is harder than wacke, and 

 differs from laterite in not being cellular ; in being finer and 

 more regular in structure, like the fracture of a brown spar ; 

 and being much heavier than an earthy rock, and a solid stone. 

 From wacke it differs in being hard and firm, and not coarse 



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