ELISHA MITCHELL SCIENTIFIC SOCIETY. 85 



crystallized quartz would seem to indicate a solidification from a 

 fluid or semi-fluid mass of aqueo-igneous origin, rather than 

 from a fused mass of purely igneous origin. 



For the production of such large crystals the mass must have 

 solidified very slowly, and have met with but little resistance. 

 The view that the dislocation of the inclosing strata was in part 

 due to the intrusion of the vein can be accepted only with cau- 

 tion. What are the inclosing rocks, and how are they related 

 to the mica veins? 



The inclosing walls are for the most part dark gray mica 

 schists, more or less horublendic, somewhat decomposed towards 

 the surface but becoming harder further down. At some mines, 

 for instance, the Presnel in Yancey county, and the Pt. Pizzle 

 (Cloudlaud) in Mitchell county, the inclosing rock has more of 

 the appearance of a schistose gneiss. But even where it is most 

 gneissic it is still highly micaceous and hornblendic. An inter- 

 esting occurrence is at the Balsam Gap mine, in Buncombe 

 county, on the Black Mountain, at an elevation of 3,500 feet.* 

 Here the walling on both sides is a slaty gneiss, which offered 

 such resistance to the Assuring force that the fissure stopped short 

 of the surface, and there lies above the mica a capping of gneiss. 

 It may be, of course, that the erosion there was not sufficient to 

 remove the capping, while at other mines now showing outcrops 

 of mica veins the rock did not oppose such resistance. Because 

 a mica vein outcrops now we may not be warranted in assuming 

 that it always outcropped. In cases where the original outcrop 

 has been covered over by newer formations the explanation is 

 simple; but where the vein never reaches the surface at all, as 

 probably at this mine, it is not so simple. Gaetzschmanf would 

 seek to explain such an occurrence by supposing a considerable 

 lapse of time between the opening and the Ailing of the fissure, 



*Fiijnred and described by \V. C. Kerr, Engineering and Mining Journal, 

 Vol. XXI, No. 13, |>. 212 and Trans. Atner. Inst. Min. Engs., L880. 



fAuf-und Udtersuchung Nntzb. Mineralien, Leipzig, 1865, p. 92, where 

 many similar occurrences are noted. Compare also Von Cotta, Erzlagerstatten, 

 1 Th., 18o9, p. 118. Grimm, Lagerst. der Nutzb. Miner, 1869, p. 100. 



