150 Journal of the Mitchell Society [March 



character of its ore is furnished only by the fragments on the dumps. 



Marhle in the pre-Camhrian near Toecane: — The rarity of marble- 

 magnetite ores in western North Carolina may be due to the fact that 

 the limestone beds themselves are rare. Their best known occurrence 

 is in a cut on the C. C. & 0. R. R. at Intermont, which is about four 

 miles south of Toecane in Mitchell County. The limestone is a coarse 

 white marble associated with gneisses and pegmatite. It is mapped by 

 Keith as being in the Carolina gneiss — a series of micaceous and gar- 

 netiferous schists and micaceous, garnetiferous and cyanitic gneisses, 

 which are believed to be the oldest rocks in the region. Keith^ de- 

 scribes the marble as occurring in two bands alternating with mica- 

 gneiss and dipping 50° S. E. The rocks are cut by a pegmatite vein, 

 which passes in places across the beds and in other places along them. 

 The upper layer is said to be 70 ft. thick and the lower layer 8 ft. 

 with a 10 ft. thick layer of mica gneiss between them. The marble is 

 white and coarsely cr.ystalline. It consists of 55% CaCOo and 45% 

 MgCOg. The contacts of the marble with the contiguous gneiss are 

 said to be sharp. Contacts with the pegmatite are equally sharp, but 

 in some places between the marble and pegmatite is a thin contact 

 vein of actinolite which grades into the marble. Inclosed in the lower 

 marble is also a small mass of actinolite and serpentine. The marble 

 is supposed to be a metamorphosed sediment interbedded with silicious 

 sediments now represented by gneisses and schists. 



A sketch of the exposure is reproduced in pi. 27. Instead of being 

 in two distinct layers as might be inferred from Keith's description 

 the section now displayed on the railroad shows the marble to be in 

 fragments separated by gneiss and pegmatite. It is possible that the 

 three masses visible in the section may originally have been parts of 

 a single bed or parts of two beds, but it is certain that their present 

 distribution is due to fracturing and intrusion by pegmatite. At the 

 south end of the section near its bottom the limestone is in contact 

 with the pegmatite and with gneiss. For half an inch from the con- 

 tact with the gneiss the limestone is bordered by a light gray zone in 

 which are many plates of a light mica resembling phlogopite, a few 

 plates of biotite and an occasional garnet. At the immediate contact 

 is a seam of light brow^l mica. 



Under the microscope a section cut across the contact zone reveals 

 the presence in it of many plates of an almost colorless mica with a 



'Mount Mitchell Folio. Geol. Atlas of the U. S. Polio 124, p. 2-3, 1905. 



