ABSTRACTS OF TAPERS 65 



ites of western North Carolina ^ were examined and it was discovered tliat 

 the Cranberry magnetite vein is much older than Juratrias time, since its 

 gangue is crushed and is penetrated by veins of iiegmatite which, so far as 

 known, occur only in the pre-Cambrian rocks of the district. Consequently 

 the ore deposit could not have owed its existence to the Bakerville gabbro, if 

 this is Juratrias. 



The gangue of the Cranberry ore is characterized by an abundance of epi- 

 dote and hornblende. The epidote is clearly derived from the feldspar of a 

 pegmatite and the hornblende from pyroxene. 



The pegmatite appears to have been an augitic variety and the magnetite 

 that forms the ore bodies is closely associated with it. 



After describing several thin sections of the ore and gangue, the conclusion 

 is reached that the ores are pre-Cambrian in age and that they were deposited 

 by an intrusion of pegmatite which brought with it richly ferriferous solutions. 



The titaniferous ores of the region, on the other hand, are believed to be 

 genetically connected with peridotites, since serpentine or some similar mineral 

 is nearly always associated with them. 



Eead from manuscript. 



Professor Bayley's paper was discussed by Professors T. L. Watson and 

 U. S. Grant, with reply by the author. 



Discussion 



Prof. T. L. Watson : Of the two principal types of magnetite deposits in 

 western North Carolina, titaniferous and non-titaniferous, Professor Bayley 

 regards the latter of pegmatitic origin, while the genesis of the former is in 

 doubt, because of lack of sufficient data regarding them. At one locality only 

 were the ore bodies found in association with limestone. 



Similar lens-shaped bodies of magnetite of varying size and richness, includ- 

 ing titaniferous and non-titaniferous varieties, occur in many localities in the 

 Blue Ridge and Piedmont Plateau provinces of Virginia. So far as these have 

 been investigated, most of them are apparently inclosed in crystalline schists, 

 with which they usually conform in structure. Some of the magnetite liodies 

 of the Piedmont province are intimately associated with quartzite and crys- 

 talline limestone, while at least a part of those of the Blue Ridge province are 

 associated with rocks of undoubted igneous origin. The geology of the Vir- 

 ginia magnetite bodies, now under investigation by the Vii'ginia Geological 

 Survey, strongly suggests that a common genesis can not be ascribed to all of 

 them, but that several different genetic types are represented. 



Prof. W. S. Bayley : Three types of magnetic ores are to be found in Ashe 

 County. So far as I know, the titaniferous ores are associated with perido- 

 tites and the non-titaniferous siliceous ones are associated with rocks like 

 those at Cranberry. These I think are pegmatitic in origin. Of course, this 

 report is preliminary only. So far as I have seen the non-titaniferous mag- 

 netites of Ashe County, they are identical in all respects with the ore at 

 Cranberry. 



' U. S. Geol. Survey, Folio No. 00, p. 8. 



V— Bull. Gkol. Soc. A.m.. V..l. .",2, 1920 



