22 



GEOLOGICAL SURVEY OF ALABAMA 



Average prices per pound paid in the South for rough-trimmed 



sheet mica of good quality, split and sorted to 



cut the sizes indicated, 1913-1918. 



*U. S. Geological Survey Mica in 1918. 



The preceding table as noted above to some extent is 

 influenced by war conditions and governmental price fix- 

 ing. The continued post-war demand for mica by the 

 electrical industries, has however not only maintained 

 the higher level of war prices, but has even resulted in a 

 material increase of these prices, extending to all grades, 

 and amounting as estimated to approximately 25 per cent, 

 or more for special grades most actively in demand. 

 Analysis of these advances in value also indicates that 

 they base largely upon the smaller sizes of mica, the most 

 marked increase in prices paid per unit area, being for 2 

 by 3, and for 3 by 4 inch. As reflecting active preferen- 

 tial market conditions and demands for these smaller 

 sizes, which must necessarily constitute the major part of 

 the output of most if not all mica mines, these facts, if 

 correctly understood and construed, are of material bene- 

 fit and importance to the mica miner. Largely increased 

 use of condenser mica also entered into these and present 

 price advances. Among special war demands influencing 

 1918 prices the larges sizes, grades 1, 2, and 3 were re- 

 quired for spark plugs for the Aircraft Production Board, 

 used in Liberty motors; grade 4 was specified for radio 

 condensers, for both navy and signal corps radio appara- 

 tus; grade 5 being used for magneto condensers for the 



