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that the ore could not be smelted, but there is no good reason for such an opinion.
Since the mines have been abandoned, the old shafts, ranging in depth from fifteen to seventy feet, are all filled in, and the country has become covered with a dense undergrowth of brush and briars. About one year ago Prof. Cox revisited these mines for a company who had in view the lease or purchase of them; it was during this visit that the gray copper above referred to was discovered. This ore had previously escaped the observation of others who had explored these mines. It is impossible at present to see the ore in place, and those who previously worked the mine give conflicting statements as to the manner in which the ore is found.
The vein-rock and associated minerals with the galena are white quartz, spathic iron, zinc-blende, copper pyrites, gray copper, tennantite, and nacrite.
The mines are now in the hands of a new company, and the latest information from their operations is that matters look well; the vein now being worked is nearly three feet wide, principally lead-ore, the balance being zinc-blende; twenty hands are at work, and the shaft is down forty-five feet. My opinion is that in time this mine will become of considerable importance, and lead to further developments of argentiferous galena in that region.
NOTES ON THE CORUNDUM OF NORTH CARO
LINA, GEORGIA, AND MONTANA,
WITH A DESCRIPTION OF THE GEM VARIETY OF THE CORUNDUM FROM THESE LOCALITIES.
The corundum formations in North Carolina and Georgia are the second in importance in the United States that have been brought to my notice; and the one in North Carolina is by far the most interesting in this country, and perhaps of any yet known, in the extent of the formation, the distribution of the corundum, and the purity of the mineral.
This mineral was first discovered in North Carolina in 1846about the time I was engaged in developing the geology of emery in Asia Minor and the Grecian Archipelago; and upon communicating to American geologists my discoveries in relation to the associate minerals of the emery in Asia Minor, and directing them to search for the same in connection with the corundum found in different parts of America, the same associates were discovered in connection with the North Carolina corundum, as well as that from other localities.
At this time there had been discovered but one detached block, but no other specimen could be discovered in that locality. There the matter rested until 1865, when C. D. Smith (to whom I am indebted for valuable information contained in this paper), assistant of Prof. Emmons, geologist of North Carolina, had brought to him by one of the inhabitants of the country west of the Blue Ridge Mountains a specimen of rock which was recognized as being corundum, and on visiting the spot this geologist discovered the corundum in situ, and a number of specimens were collected. 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 colors of the corundum as found along this zone of outcrops are blue, gray, 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 serpentine rocks, and outside of serpentine it has not been found. These chrysolite rocks belong to a regular system of dikes, which have been traversed for the distance of about one hundred and ninety miles. This system of dikes lies on the north-west side of the Blue Ridge, 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 relative position to the Blue Ridge.
The serpentine appears at intervals along this whole line of one hundred and ninety miles. There is a corresponding system of dikes traversing the southern slope of the Blue Ridge, but not so regular and compact as the system on this northwest 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 have been found. From Mitchell County to Macon the serpentine is usually inclosed in a hard crystalline gneissrock, which bears rose-colored garnets, kyanite, and pyrite. After its shifting to the right it occurs in hornblendic beds and gneiss. At Buck Creek and thence south-westward the hornblend beds assume very large proportions, and instead of common feldspar 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 dike systems, whereas they have no connection whatever.
According to them the northern system cut through the Blue Ridge at right-angles, and then turn back on the opposite side of the ridge.
Now there is 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 exists 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 chrysoliterock 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, etc.
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 unmistakable 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 lamellæ; also its diaspore is rare, but when found is prismatic, affording the finest perfect crystals yet seen, from which M. Dufrenoy made his last study of the crystallography of this mineral; and the emery is associated with calcareous rock overlying gneiss. The Kulah emery from the same part of the world is equally in calcareous rock, and has very little chloritoid or chloritic mineral associated with it.
The Naxos and Nicaria emery of the Grecian Archipelago is also in connection with calcareous rock, but has no chloritoid associated with it, but in its place black tourmaline is abundant.
While in the above localities the rock bearing the corundum is calcareous, that in Chester, Mass., is in talcose slate, and saponite with hornblendic gneiss immediately on one side of the vein, and is accompanied with a large amount of magnetic oxide of iron. Tourmaline also abounds in this corundum, and like the Asiatic variety contains rutile, ilminite, etc.
In the localities forming the subject of this memoir the following minerals are deserving special notice.
This mineral occurs in finer and more beautiful variety than in any yet known locality. The masses in many instances are very large, weighing six to eight hundred pounds, having fine large cleavages, and are remarkably free from foreign ingredients. The crystals are also fine, and in some instances of great size and beauty. Two of them discovered by M. Jenks, and now in the possession of Prof. Shepard, have been described by him. They are respectively three hundred and twelve and eleven and three fourths pounds in weight. The largest is red at the surface, but within of a bluish-gray. The general figure is pyramidal, showing, however, more than a single six-sided pyramid, whose summit is terminated by rather an uneven and somewhat undefined hexagonal plane. The smaller crystal is a regular hexagonal prism, well terminated at one of its extremities, the other being drusy and incomplete. The general color of this crystal is a grayish-blue, though there are spots, particularly near the angles, where it is of a pale sapphire tint. Its greatest breadth is six inches, and its length over five. Some of the lateral planes are coated in patches with a white pearly margarite.