GOLD MINING IN COLORADO. 497 



The distribution of ore in the vein is not uniform. Some portions of 

 the ground, for considerable distances, both horizontally and vertically, are 

 barren; the walls approach each other; the vein matter pinches out, or, some- 

 times, the vein, where preserving its width, is filled with barren rock. In 

 some places the fissure is filled with a good vein of stamp-rock, with little or 

 no first-class ore ; in others the solid seams of sulphurets, the copper and iron 

 pyrites, attain and preserve for considerable distances, a width of two feet 

 or more. Commonly, however, as has just been stated, the vein, where pro- 

 ductive, consists of a seam of gold-bearing pyrites, eight or twelve inches in 

 width, with an accompanying belt of pay-ground, having the ore more or less 

 liberally distributed through it, and affording stamp-rock of fair quality. The 

 average yield of the stamp-rock of this lode is six or seven ounces of retorted 

 amalgam per cord of ore. The ounce of amalgam is worth from $16 50 to 

 $18, coin. The cord contains from seven to eight tons. The yield is accord- 

 ingly about $14 or $16, coin, per ton. 



As nearly as could be ascertained from the officers of the Bobtail mine, 

 working on the western portion of the lode, the proportion of first-class ore 

 to the second-class or stamp-rock, was about one-tenth; while the whole 

 amount of ore of the two- grades was estimated to be from one-third to one- 

 half of all the rock raised from the mine. 



The lode is clearly traced and is developed for 800 feet in length. Un- 

 fortunately that extent of ground, itself not more than enough for one well- 

 managed mine, is divided up into six independent claims, some of them very 

 short, not only increasing greatly the costs of superintendence and general 

 management, but presenting great hinderances to the economical opening and 

 working of the ground. These claims, beginning at the west end in the ra- 

 vine and proceeding easterly, are as follows: 



Feet. 



The Bobtail Gold Mining Company owning - 433^ 



The Sterling Gold Mining Company owning. , 66| 



The Black Hawk Gold Mining Company owning 72 



The Field Gold Mining Company owning 33^ 



The Trust Gold Mining Company owning 66^ 



The Sensenderfer Gold Mining Company owning 128 



800 



63 r 



