COLLECTIONS IN ECONOMIC GEOLOGY AND METALLURGY. 83 



This is sorted out in the rock house, about 10 per cent, of the material 

 hoisted being sent to the dump. 



The mine skip dumps its load onto a screen of parallel bars set 4 

 inches apart, and most of the material passes over this screen, and falls 

 onto the main floor. Here the material is sorted, and then crushed in 

 Blake crushers, and the barren material rejected. Large pieces, how- 

 ever, have to be broken before being fed to the crushers. The material 

 falling through the 4-inch screen, and also that from the flrst set of 

 crushers, passes over a 2-inch screen. What passes over this screen 

 is again sorted, and then crushed small enough for the stamp mill. 

 What goes through the 2-inch screen is sent directly to the stamps. 



The stamp mill is 11 miles from the mine, and the crushed ore is 

 taken to it over a narrow-gauge railroad in cars holding about 12i tons. 

 In the rock house assorting the small masses are picked out, cleaned 

 as much as possible, and then packed in barrels, and sent direct to the 

 smelting works. This material is known as barrel work, while the 

 material sent to the stamp mill is called stamp work. 



To illustrate the general character of the deposit the following spec- 

 imens are shown : 



(1) A single speciuieu illustrating surface copper or " float," A small mass of cop- 

 per completely coated by oxidation products. (54270.) 



(2) Free cojiper, in i-ough crystals. (54281.) 



(3) Free copper, small characteristic mass. (54325.) 



(4) Free copper, heavy leaf. (54324.) 



(5) Free copper, coarsely arborescent, commonly called " horn copper." (54326.) 



(6) A very characteristic sample of the ore, showing the amygdaloids of calcite, 

 and considerable free copper. (54316.) 



(7) A very characteristic sample of the ore, showing the calcite deposited on the 

 copper in the amygdules. Taken from the hanging wall. (54313.) 



To illustrate the association of free silver with free copper three 

 specimens are shown : 



(1) Free silver and free copper together, both roughly crystallized. (542d3. ) 



(2) Free silver in calcite, separate from the copper. (54297.) 



(3) Free silver and free copper, separate, both crystallized; associated with prehn- 

 ite and quartz. A characteristic sample of material found in rich copper chutes, 

 generally carrying silver. (54296.) 



Owing to the uncertainty in the lower limit of the deposit, it is some- 

 times impossible to tell where the barren vein rock ends and the foot 

 wall begins, and for this reason, in the sections, the foot wall has been 

 omitted, except where it is quite distinct from the barren vein roclc. 



To illustrate the bed at N"o. 1 shaft, the following specimens are 

 shown. A full section of the bed at the end of the second level, 300 

 feet north of the shaft in a stope 80 feet high, shows — 



(1) Trap rock, from the hanging wall. (.54275.) 



(2) Trap, 12 feet from tlic lianging wall, apparently a horse. (.54280.) 



(3) Ore, 15 feet from hanging wall ; amygdaloid rock witli free copper. A charac- 

 teristic specimen. (54279.) 



(4) Poor vein rock, from foot wall 20 feet from hanging wall ; amygdaloid, con- 

 taining a little free copper. (54274.) 



