ELISHA MITCHELL SCIENTIFIC SOCIETY. 95 



only by compariug the percentage yield of cut mica from block 

 mica, as twisted or A mica and stained mica is not included in 

 cut mica. 



Prof. Shaler speaks also of the relatively small amount of 

 gangue in the richer parts of the vein compensating for the in- 

 creased expense of mining Carolina mica. This has less to do 

 with the yield of cut mica than the quality of the blocks. The 

 greater or less preponderance of gangue may, and doubtless 

 does, influence the mining account, and so, indirectly, the balance 

 sheet ; but the value of 100 pounds of block mica depends less 

 upon the percentage of gangue than upon the quality of the cut 

 mica obtained from it. The assertion that Carolina rough mica 

 yields less cut mica than that from New Hampshire remains to 

 be proved. 



CONCLUSION. 



In bringing this article to a close it seems necessary to ex- 

 plain why no statistics have been given. Such as are accessible 

 will be found in a compilation by the writer to be published 

 shortly in the "Mineral Resources of the United States for 

 1887," U. S. Geol. Survey. In this volume will be found also 

 a more concise and less technical account of the industry, and 

 those who wish a bird's-eye view of the matter are referred to it. 



North Carolina, for several years past, has contributed over 

 (50 per cent, of the mica produced in the United States. With 

 New Hampshire, she produces fully 95 per cent, of the better 

 quality of mica in the country, and while, indeed, it cannot be 

 asserted that her mica is better than that from other sources, it 

 is just as good, and the statistics above referred to show that it is 

 mined at less cost than New Hampshire mica. 



I must say, however, t hat in my opinion these statistics are 

 erroneous. There cannot exist such a difference between the 

 effective value of a dollar in North Carolina and New Hamp- 

 shire as they reveal. It is impossible to believe that one dollar 

 in North Carolina yielded $8.93, and in New Hampshire only 

 20 cents, especially when we consider that in the former State 

 G 



