S-Jfc TACTS IN AMERICAN MINING. 



The capital invested in mines and mining is returning about 20 

 per cent. The average earnings per miner is at least 12s. per day 

 on those mines which are opened. In some of the well known 

 mines, the yield averages all the year round £1 per day for every 

 hand employed. 



In the mills of Virginia city .alone they use no less than 923 

 pans of various makes, including the Knox, AVheeler, Hepburn, 

 Varney, "Wakelee, and Plain, and 400 settlers, agitators, grinders, 

 barrels, tubs, and concentrators. 



Fine gold — In the year I860 the yield of gold was found to 

 be in the Pine-tree district only 40 per cent, of the actual 

 contents, owing to its being so fine as to be invisible to the naked 

 eye. In the Mariposa district, for the same reason, the gold 

 quartz which yields £10 to £12 10s. per ton used only to give 

 40s. to 60s. In the Pine-tree the whole cost of treatment only 

 averages 24s. per ton. 



Reduction works. — In the State of Nevada there are no less 

 than 170 ; and their cost is put down at two millions sterling.* 



Aqueducts. — One is now being constructed to convey the w r est 

 branch of the Carson River 30 miles to the Empire City ; 

 another, known as the Humboldt Ditch, will be no less than GO 

 miles in length. Both of these are built to convey water to the 

 mines. 



Run of gold in quartz reefs. — Careful and systematic obser- 

 vation has demonstrated that they are rarely worked to a profit 

 for more than 2 consecutive miles, and that pay rock rarely 

 extends for more than 1,000 feet along a vein. A large mineral 

 vein, however, is often traceable for 30 or 40 miles in a 

 straight line, the rich portions being often far apart, and the 

 intervals barren. This observation is the result of a very large 

 experience, and no doubt applies to this as well as other countries ; 

 though I doubt if it has been made useful as a valuable item to 

 the explorer to guide him in his researches. 



The Comstock lode, believed to be the richest in the world, 

 embraces an area of 3 miles in length and a third of a mile 

 in width, equal to the area of a square mile. It produces 

 annually two and a half millions sterling, while the loss on the 

 ores represents not less than a third of the entire value ; so that 

 something like three-quarters of a million is allowed to go to 

 waste every year. About 5.000 men are employed, and their 

 average earning is equal to £500 per man per annum. The ex- 

 cavations in tunnels, shafts, &c, aggregate G7| miles. The 

 timber for mine use and firewood costs annually £200,000. 



*Clande informs us, after examination of some samples of Californian pyrites, that it 

 contains gold, silver, copper, lead, cobalt, iron, arsenic, sulphur, and silica, in varying pro- 

 portions. In three samples the gold has ranged from 8J to 98* ounces per ton, and the silver 

 from 3 ozs. IS dwts. to 11 ozs. 16 dwts. In the Grass Valley pyrites the bullion consists of 

 52 per cent, gold, and 48 per cent, silver— a proportion that would defy any attempt at ex- 

 traction by chlorinatioD, 



