Remarks on the Gold Mines of Virginia. 121 



veins in place, and that the loose fragments of quartz which are scat- 

 tered in profusion, upon various parts of the ground, are attributable 

 to a similar origin. 



The main vein, hitherto worked in this tract, appears, in some 

 places, prone to divide into strings : sometimes several, perhaps not 

 longer than a finger, proceed parallel, or nearly so, being separated 

 only by portions of the slaty rock : their separation appears, in gen- 

 eral, to be only temporary ; for the greater part, they again con- 

 verge, and unite in a main vein, and the gold is observed to be more 

 abundant in these strings than in larger veins. There is much iron 

 accompanying the ore of gold. It imparts a red color, more or less 

 intense, and the pulverized quartz is almost always red or brown. 

 There is here an iron ore regarded by some as a hydrated oxide. It 

 appears to have proceeded from the decomposition of iron pyrites, 

 which, in many places, are still found fresh and brilliant ; in other in- 

 stances, splitting, rusting, and undergoing decomposition, the result of 

 which is, that a portion of this mineral passes off in the form of sul- 

 phate of iron or copperas, which water easily dissolves, while a large 

 portion remains in the form of a vesicular and corroded dark brown or 

 red oxide. So far as this ferruginous matter contains gold, it is doubt- 

 less derived from the iron pyrites, which appears to be more or less 

 auriferous, and when it is decomposed, the gold, being insoluble ei- 

 ther in the water or in the sulphuric acid which is generated, remains 

 mixed with the oxide of iron, that constitutes the residuum. There 

 is, in some cases, a gradual passage from the brilliant yellow pyrites 

 into this brown or black iron ore. 



The strata found in this tract, are varieties of slate and of various 

 other rocks, frequently associated with this primary family. They 

 are remarkable for being placed in a position, nearly or quite per- 

 pendicular : the strata stand on edge, or if inclined, they form but a 

 small angle with a vertical line, and consequently, nearly or quite, 

 a right angle with the horizon. 



This position of the rocks is very advantageous to the working of 

 the mines, because, the veins of auriferous quartz, being laid be- 

 tween the layers and strata of the rock, are therefore, like it, nearly 

 or quite perpendicular — consequently, the working of the vein cre- 

 ates a vertical adit, in which the miners can stand erect, and when 

 it is wrought quite to the surface of the ground, the opening will be 

 a perpendicular fissur,e, of easy access. 



Vol. XXXII.— No. 1. 16 



