GOLD MINING IN COLORADO. 543 



300 feet. Between the two shafts, considerable stoping had been done, but 

 the gi-ound was whole below the 300-foot level. 



From the developments thus made the lode appears to possess the char- 

 acteristics of a well-defined fissure vein. Its course is north 85° east. The 

 dip is slightly to the south, about 85° from the horizon. The walls are 

 smooth and very regular. They are from two to six feet apart, and, in the 

 stopes visited at the time referred to, the whole space was filled with pay- 

 ground. The gangue is a quartzose material, generally resembling that al- 

 ready described as the characteristic filling of the veins of this region. The 

 ore is chiefly iron and copper pyrites, carrying, in bunches or pockets, con- 

 siderable quantities of galena and zincblende, particularly the last named. 

 There is commonly a seam of first-class ore, associated with a wider belt of 

 milling ore. 



During the past year the ground has been unusually productive. Ac- 

 cording to the statements of the proprietors, not more than one-eighth of all 

 the rock broken in the mine is thrown away as poor ; while one ton of ore in 

 ten is said to be fit for smelting. The value/ of the milling rock is said to be 

 very high, yielding an average of 12 ounces of amalgam to the cord, the 

 ounce being worth about or little more than $13, in coin. According to this, 

 the milling ore yields about $21 per ton, in coin. The average contents, by 

 assay of over 400 tons of smelting ore sold at the Smelting Works, was 

 nearly 3 ounces of fine gold and 18 ounces of fine silver per ton. 



The mine has not always been in such good fortune. When first opened 

 the surface quartz was taken out about 40 feet deep, and was worked with 

 profit. The shaft then encountered poor ground, which it passed through for 

 180 feet. It has since been shown that there was excellent ground only a 

 few feet from the shaft, which remained undiscovered because no drift was 

 run toward it from the shaft. At the depth of 180 feet the shaft reached 

 ore-bearing ground, that yielded about 7 ounces to the cord, or $12 to $13 

 per ton. The yield has greatly improved since opening the stopes between 

 the shafts. 



In August, 1869, there were 24 men employed at the mine, 16 of whom 

 were stoping. With this force about 30 tons of ore per day were mined and 

 raised. Sinking cost $15 to $20 per foot ; stoping $12 or $18 per fathom. 



