66 HOLLAND : MICA DEPOSITS OF INDIA. 



So far, mining has been carried on only at CheramMdi by Messrs. 

 Morres and MacKinlay, but trie quality and size of the mica would 

 justify fairly extensive operations. 



B.G. q. M. . D, F. B. G. 



Fig. 1 6. Section showing the common structure of the pegmatite veins 

 in south-east Wain&d. 



Sheets of mica have been obtained up to 3 feet in length, but as 

 the workings have at present only reached depths of a few feet below 

 the surface, much of the mica now obtained has suffered from weather- 

 ing. In spite of this, considerable quantities of mica of high quality 

 are being obtained, and when mining has been carried to greater 

 depths and into fresher rock, the quality will no doubt improve. 



Owing to the almost entire absence of accessory minerals, the 

 larger plates are not spoilt, as is so frequently the case elsewhere, by 

 inclusions of garnets, tourmaline, etc., and it is an interesting fact that 

 no trace of this latter mineral has been found in the Waindd pegma- 

 tites (cf. Coorg). The country rock is usually a soft biotite-gneiss, 

 in which mining should be easy and inexpensive. 



References to some of these localities are incidentally made by 

 R. Brough Smyth in his report on the gold mines of the Wainad 

 (pp. 6 and 37). 



Salem. 

 Mica occurs as a constituent of the contemporaneous pegmatite 

 veins which traverse the great granite intrusions forming the conspicu- 

 ous drugs in the south-west of the district and in the Erode vallev. 

 Plates of brownish muscovite, measuring a foot across the cleavage 

 planes, were obtained by Mr. C. S. Middlemiss near Iddapadi, and a 

 small amount of work has been attempted in the villages of Chinna- 

 ( 56 ) 



