GEOGRAPHICAL AND GEOLOGICAL DESCKIPTIOX OF GOLD BELTS. 23
main parallel to the schistosity of the rock, though not uncommonly they cut the same at low angles. To a large extent they are aggregated in a zone of numerous narrow and discontinuous lenses and stringers through more or less definite bands of the gneiss, which, taken altogether, form the vein. This is well illustrated in Tig. 2. ]tfr. Becker has designated such a system, a " stringer-lead." ' In these narrow, sharply-banded gneisses and schists of different material, such as they are in this part cf the Georgia belt, it is natural that the fracturing force, once exerted in a certain band, should have been more or less confined to this one, both longitudinally and transversely, the walls of the band forming the walls of the ore-body. This is in fact the case. At times the Assuring is confined to the light-colored micagneisses, at other times to the dark-colored ferromagnesian gneisses and schists. The " brick-bat " schists rarely contain ore-bodies. The thickness of the veins is from, less than 3 to as much as 20 feet; they are frequently close together, separated by non-auriferous bands of gneiss; and the total width of the ore-bearing ground reaches as much as '200 feet (Singleton mine, Dahlonega). The extent of Assuring must depend largely on the degree of homogeneity of the material, as well as on the intensity of the fracturing force. Where the rock is of homogeneous composition and the force uniformly exerted, the effect would be a more or less evenly distributed shattering, with few gaping fissures, and the whole mass would be permeated by the gold-bearing solutions, with the formation of auriferous and pyritic impregnations, with some small quartz-stringers. At the Hedwig mine, near Auraria, for instance, regular quartz masses of any size are altogether absent, the ore-body being composed of soft, sandy, mica-gneisses and -schists containing only a few, small and isolated quartz-stringers. Again, under •different conditions, the effect was the production of a large number of small open fissures, inducing the consequent formation of numerous small lenticular quartz-stringers; and such is the usual case in the Dahlonega ore-bodies (fig. 2, p. 22). Or, where the rock mass was of still greater heterogeneity, and the forces of greater or more varied intensity, lenticular fissures have been opened, of such size and extent as to allow a more or less complete filling by solid auriferous and pyritic quartz, from 3 to 14 feet in thickness; while, further along the strike, though the fracturing extends to the same width and the walls hold out, the intervening space of country has simply been shattered, or opened only in small spaces, but was nevertheless filled with pyritic impregnations and quartz-stringers, (as at the Franklin mine in Cherokee county, where these barren portions of the vein are called horses). But the
1" Reconnoissanee of the Gold Fields of the Southern Appalachians," Sixteenth Annual Report of the 77. .S. Geological Survey, 1894-5, part iii, p. 283.
