I 



58 HOLLAND: MICA DEPOSITS OF INDIA. 



mica crystallized before the quartz when the rock was formed, and 

 was solid when the quartz was still in a liquid or viscous condition. 

 As the magma from which the quartz finally crystallized probably 

 passed through a long viscous stage, it is natural to infer that the 

 mica-crystal was dislocated and faulted out by movement of the 

 viscous material, and disturbance of this material during the crystal- 

 lization of the quartz would result in the formation of crystals from 

 numerous centres, whose growth would soon give rise to mutual in- 

 terference, and produce a minutely granular mass in which the more 

 prefectly crystallized portions would be embedded as clear bodies in a 

 sugary matrix. 



v MADRAS PRESIDENCY. 



Coimbatore. 



An unsuccessful attempt was made to work the muscovite occurring 

 associated with corundum, chrysoberyl and a zinc-alumina spinel in 

 the peculiar, coarse felspar-veins (corundum-syenite pegmatite) exposed 

 near the small hills of elaeolite-syenite near Karutapalaiyam, 3 miles 

 north-west of Kangayam in the Coimbatore district. The numer- 

 ous pegmatite -veins in this area, and near the village of Padyur, a little 

 further to the north, often contain good muscovite-crystals, but they 

 are not sufficiently large and abundant to pay for mining mica alone. 1 



Ganjam. 



The Collector of the district reports the occurrence of poor mica at 

 the following places — 4 miles north and 2 miles east of Rayagada and 

 Guma hills of the Parlakimidi estate ; Sisunda and Jillundi in the 

 Gumsur taluk. 



Nellore. 



The mica-mining area in the Nellore district differs from that of 

 Bengal in an important physical feature. In Bengal, as already ex- 



1 Described in a separate memoir. Mem. Geol. Surv. Ind., Vol. XXX, part 3 

 (1901). 



( 43 ) 



