12 HOLLAND: MICA DEPOSITS OF INDIA. 



mica supplies of the world. The importance of this circumstance is 

 further accentuated by the fact that the remarkable physical properties, 

 which have secured for mica its extensive use in the Arts, are not pos- 

 sessed by any other mineral, and are not, and not likely to be, 

 imitated by any artificial substance. The mica-miner should not be 

 surprised, therefore, if the Government show an inclination to temper 

 the encouragement given to his industry with restrictions intended to 

 discourage his wasteful methods of mining and the tendency which he 

 has shown, not unnaturally, to secure immediate returns by wantonly 

 excavating shallow workings over large areas. It is hoped, neverthe- 

 less, that the criticisms which accompany the advice given in a sub- 

 sequent chapter will be found to benefit the mica-miner as much as the 

 holder of mineral rights, the interests of both being necessarily inter- 

 dependent. 



As a further object, this paper is intended to convey to the mica- 

 miner a brief resume of the nature and history of the mineral in which 

 he is so largely interested ; and, finally, it is made the means of record- 

 ing, for the information of mineralogists interested only in scientific 

 questions, the new facts of value concerning the natural history of mica 

 which the detailed study of its Indian occurrences has revealed to the 

 writer and his colleagues. 



The use of simple names expressing the very prominent lustrous 

 character of minerals like the micas, talc and selenite has made it diffi- 

 cult to determine the exact species referred to in any but the most 

 recent scientific literature. 1 The highly perfect basal cleavage, which 

 permits both mica and talc to be split into thin laminse, has helped to 

 maintain the confusion which exists in the popular mind between these 

 two species, but which is now becoming removed gradually by the 

 more extended use of the mineral mica in the Arts and its commoner 

 appearance as an article of ordinary trade. 



1 Selenite, cre^vtrrn (Dioscorides, Civ. A.D. 50), now used for the crystallized 

 hydrous sulphate of lime or gypsum, was the equivalent of Pliny's lapis specularis, 

 which, however, from its use (to produce a whiteness on the " Circus Maximus ") 

 was probably mica. 

 ( 2 ) 



