Pratt — Corundum in North Carolina. 295 



Aet. XXIX. — On two new Occurrences of Corundum in 

 North Carolina; by Joseph Hyde Peatt. 



Where formerly corundum was supposed to be rare in its 

 occurrence and to be found in quantity only in the basic mag- 

 nesian rocks, it is now known to occur in various types of 

 rocks and in quantity, in syenites, gneisses and schists. Many 

 new occurrences have been discovered during the past few 

 years, some of which give indications of being of considerable 

 economic importance, while others are only of scientific value. 

 In the present paper two new occurrences are to be described, 

 that have been observed in North Carolina, one in an amphi- 

 bole-schist and the other in a quartz-schist. 



Corundum in Amjjhibole- Schist. 



At the Sheffield mine in Cowee township, Macon County, 

 North Carolina, corundum has been mined in a saprolitic rock 

 at various times for a number of years. While sinking a shaft 

 eight feet square to penetrate the depth of the corundum-bear- 

 ing saprolite, the solid unaltered rock was encountered. The 

 shaft was 87 feet deep and showed the following sequence 

 downward. The first 12 feet was through the saprolitic rock, 

 in which there were seams, a few inches wide, of kaolin ; the 

 next two feet were corundum-bearing ; from 14 to 28 feet the 

 same saprolite was encountered and then another two feet that 

 was corundum-bearing, followed by another ten feet of the 

 saprolite and two more feet of the corundum-bearing rock ; 

 from 42 to 65 feet the rock began to be less decomposed and 

 from 63 to 66 feet another seam that was corundum-bearing 

 was encountered. From this point the rock became more and 

 more solid, until at 77 feet the fresh rock was encountered. 

 These various seams in the rock are very pronounced and are 

 dipping 30° toward the west near the top, but become nearly 

 horizontal nearer the bottom of the shaft. The seams of 

 decomposed feldspar observed near the top of the shaft become 

 less and less kaolinized downward, until in the solid rock the 

 seams are of a pure plagioclase feldspar. In the hard rock 

 exposed there are two seams of corundum similar to those 

 above, although in the fresh rock the corundum seams are not 

 as pronounced as in the saprolitic rock. There is often consid- 

 erable of the feldspar bordering the seams of corundum. The 

 general trend of the rock is about 1ST. 5-10° E. 



From what could be seen of the solid and the saprolitic rocks 

 the corundum occurs in seams a few feet in width at intervals 

 in the rock, and while the corundum may be ten or more per 

 cent in these veins, its percentage in the rock, that it would be 

 necessary to mine, would not probably be over three or four. 

 The actual width of the dike is not known, but the saprolitic 



