MINES OF GOLD HILL. 
313 
GAS. 
The mine as a whole is well ventilated and objectionable gases have little 
opportunity to accumulate. The northern part of level 10 could not be entered 
at the time of visit, on account of impure air, but this drift has only one connection 
with the surface and the air is nearly stagnant. There is apparently no con¬ 
spicuous influx of gas from the rock into the mine at any point. 
CALEDONIA MINE. 
The Caledonia is situated about a quarter of a mile northeast of Mound, on a 
low southwest spur from Gold Hill. It has been developed by three shafts and 
some irregular drifts and crosscuts. The lode strikes about N. 30° E., and has 
been explored for a length of about 500 feet and a depth of 250 feet. The general 
country rock is granite, which is cut by an irregular dike of phonolite, shown on 
the geological map (PI. II, in pocket). This phonolite turns as it is followed down, 
until at a depth of 150 feet it becomes a nearly horizontal sill extending to the 
eastv of the workings. The lode is a well-defined sheeted zone, dipping 75° or 
80° SE. It cuts through the phonolite without perceptibly faulting it. The ore 
occurred in rather irregular bunches in the phonolite or in the granite immediately 
above or below the phonolite. The maximum length of the pay shoot was about 
300 feet and practically no ore has been found at a greater depth than 100 feet. 
The ore is said to have been all more or less oxidized. The gross output of the mine 
has been about $140,000, most of which was produced in 1894 and 1895. 
CARDINAL SHAFT. 
The Cardinal shaft is situated on the point of a ridge a few hundred feet south 
of the Caledonia. The production is said to be at most 1,000 tons of ore containing 
about $20 per ton. The incline shaft descended at an angle of 70° to a depth of , 
265 feet and two levels are turned. The vein is in granite, but crosses a narrow 
phonolite dike 100 feet north of the shaft. The direction of the vein is northerly, 
the dip 70° E. A well-defined hanging wall is strongly marked by horizontal 
striations. The vein is about 1 foot wide and consists of crushed granite. A 
streak of galena was found on the hanging wall near the bottom of the shaft, also 
some calaverite. Ore has been stoped 3 feet wide for about 75 feet north of the 
shaft on level 1, but the shoot was not found on level 2. Some good ore was lately 
encountered in the bottom of the shaft. 
