EMERY 265 



him by ono of the inhabitants of the country west of the Blue Eidge Mountains a 

 gpecimen of rock which was recognised as being corundum, and on visiting the spot 

 this geologist discovered the corundum in situ, and a number of specimens were col- 

 lected. Since that time public interest has increased in relation to this substance, and 

 it has been discovered in such quantities as to make it an object of interest to the arts 

 as a substitute for emery, and very rapidly other localities were brought to light along 

 a distance of forty miles. 



' The colours of the corundum as found along this zone of outcrops are blue, grey, 

 pink, ruby, and white. Sometimes it has broad cleavage faces, and then again it 

 occurs in hexagonal prisms. One hexagonal prism weighed over three hundred 

 pounds. There is a difference in the cleavage and the associate-minerals at different 

 localities. 



' In the development in North Carolina the corundum occurs in chrysolite or ser- 

 pentine rocks, and outside of serpentine it has not been found. These chrysolite rocks 

 belong to a regular system of dykes, which have been traversed for the distance of 

 about one hundred and ninety miles. This system of dykes lies on the north-west side 

 of the Blue Kidge, and has a strike parallel to the main mass of the ridge, and has an 

 average distance from the summit of the ridge of about ten miles. It continues this 

 strike to the head of the Little Tennessee River, say from Mitchell to Macon County, 

 one hundred and thirty miles. Here the ridge curves around the head of the 

 Tennessee, and falls back about ten miles to the north-west. In conformity with this 

 elbow in the ridge, the disturbing force shifts to the north-west and re-appears at 

 Buck's Creek, having the same relative position to the Blue Eidge. 



' The serpentine appears at intervals along this whole line of one hundred and 

 ninety miles. There is a corresponding system of dykes traversing the southern slope 

 of the Blue Eidge, but not so regular and compact as the system on this north-west 

 side, nor are the outcrops so frequent. The main mass of the ridge bears no evidence 

 of having been disturbed at all, at least none has been found. From Mitchell County 

 to Macon the serpentine is usually enclosed in a hard crystalline gneiss, which bears 

 rose-coloured garnets, cyanite, and pyrite. After its shifting to the right it occurs in 

 hornblendic beds and gneiss. At Buck Creek and thence south-westward the horn- 

 blende beds assume very large proportions, and instead of common felspar have in 

 them albite, making an albitic syenite. At Buck Creek (which is named Cullakenih) 

 the chrysolite covers an area of about three hundred and fifty acres. One or two 

 observers have fallen into the error of confounding the two dyke systems, whereas 

 they have no connection whatever. According to them the northern system cuts 

 through the Blue Eidge at right angles, and then turns back on the opposite side of 

 the ridge. Now there are no such phenomena connected with these outcrops. They 

 evidently belong to separate systems. The outcrops along the northern system 

 occur at intervals ranging from one to fifteen miles. The belt or zone along which 

 these outcrops occur never exceeds four miles in width on the northern side of the 

 ridge. On the opposite side the system is not so well defined, and the outcrops are 

 rarer. 



'Upon these serpentine beds there exist chalcedony, chromite on some of them, 

 chlorite, talc, steatite, anthophyllite, tourmaline, emerylite, epidote on some of them, 

 zoisite, and albite, with occasionally asbestus and picrolite, as also actinolite and 

 tremolite. The corundum at some places seems to occur mostly in ripidolite in 

 fissures of the serpentine. At Cullakenih the corundum with its immediate associates 

 is in chlorite, except the red variety, which is in zoisite, containing a minute quantity 

 of chrome. 



' Throughout all the range of rocks for the great extent referred to, corundum forms 

 a geognostic mark of this chrysolite rock, just as it does of the calcareous rock bearing 

 corundum described by me in Asia Minor. They belong to the same geological epoch, 

 and overlie the gneiss. 



' The closest investigation shows that the chrysolite in North Carolina takes the 

 place of calc-rock in Asia Minor ; that these are invariably the gangue-rock in the two 

 different quarters of the globe; but as remarked above, the contiguous rock shows 

 them both to be of the same geological period, overlying directly the primary rocks ; 

 and both of them are also identical geologically with the Chester emery-formation of 

 Massachusetts. 



' While all the localities of corundum and emery I have examined exhibit certain 

 marked and prominent characteristics common to them all, and evince unmistakeable 

 evidence of geological identity, yet each locality has its peculiar characteristics. In 

 all cases, however, the masses of corundum give evidence of having been formed by a 

 process of segregation, as described in my memoir on the Asia Minor emery. 



' In Asia Minor the Gumuch-dagh emery has but little black tourmaline associated 

 with it, and instead chloritoid in crystals or lamellae ; also its disapore is rare, but 



