350 Transactions of the Geological Society of Pennsylvania. 



would come back and open into the sides or banks of the ravine, 

 guided by the gold, and at last, discover valuable bodies of gold ore. 

 Many instances of this kind are notorious in North Carolina and Vir- 

 ginia." The branch gold mines of the U. States, are supposed to 

 have yielded 6,000,000 of dollars, most of which is v/orked up in 

 jewellery, and not in coinage. 



Three deposit mines in Georgia have yielded 500,000 dollars, 

 and Mr. Taylor confidently anticipates that the gold deposits of the 

 United States will yield far larger returns than those of Brazil, Co- 

 lombia, and the Urals united. 



The explorations for gold have not, as yet, been carried to a great 

 depth, the greatest not exceeding one hundred and fifty feet, and few 

 of the shafts are over one hundred feet, and most do not exceed twen- 

 ty or thirty. These excavations are too shallow to afford satisfactory 

 information respecting the gold, and the digging is often abandoned 

 upon the slightest unfavorable appearance such as the narrowing of 

 the vein, its dislocation, or its becoming shattered, for there is much 

 appearance of disorganization in the veins and rocks. Pyritical ores 

 constitute the mass of the ores in Columbia, the Brazils, and the 

 United States ; above the depth of one hundred feet, they have been, 

 in this country, partially decomposed ; the yellow ores have been 

 converted into brown, red and purple hydrates of iron, and a portion 

 of the gold they contain having thus become uncovered, is accessible 

 to amalgamation, while a large portion more is, or can be developed 

 by the assay by fire. 



Most of the gold is extracted by amalgamation, after stamping un- 

 der water, and the residuum still contains gold. 



Messrs. Andres Del Rio and John Millington, as a committee fi:om 

 the Geological Society of Pennsylvania, have investigated the Rap- 

 pahannock gold mines in Virginia, situated on the river, about ten 

 miles from Fredericksburgh ; the tract is about two hundred and 

 thirty yards wide by an average length of upwards of nine hundred 

 yards. 



The metalliferous veins consist of hard quartzoze rock between 

 walls of decoraposed talcose slate. A portion of loose red soil by 

 washing two handfuls of it gave a considerable quantity of minute 

 granular gold, and similar results were obtained by washings in other 

 places. A principal auriferous quartz vein is from two feet six inch- 

 es to three feet six inches wide : it stands vertically between walls 

 of talcose slate ; there is also, on either side, a vertical bed of auri- 



