Page 213 - The Geology and Ore Deposits of Sierra County, New Mexico - Bulletin 10

MINING DISTRICTS 209
The ore occurrences are similar to those found elsewhere in the range. The ore minerals are chalcopyrite, cuprite, malachite, azurite, galena, anglesite and cerusite, with gold and silver ac- companying. The property has been prospected along the outcrop by several pits and short tunnels.
FLUORSPAR-CALCITE-SILICA VEINS
South of the galena-fluorspar veins on both the east and west slopes of the Sierra Caballos, extending approximately from the Marion mine to the southern extremity of the county and beyond, there are a number of veins which are nearly vertical and strike east. These veins, which are valuable mainly for their fluorspar content, have been discussed by Johnston 68 in considerable detail. Some of them contain a small amount of galena, which may in some instances and under the proper price incentive, become of economic importance as a by-product in the recovery of the fluor-
spar of the veins.
SHANDON (PITTSBURG) PLACERS
LOCATION AND GEOGRAPHY
The Pittsburg district includes the southern part of the Sierra Caballos, in and near Apache Canyon. The district is the southern extension of the Caballos district, and figure 19 shows that portion of it in which the Shandon or Pittsburg placers are located. Pittsburg is a small settlement at the Junction of Apache Canyon and the Rio Grande, and Shandon, five-eighths of a mile to the north, is at the junction of Trujillo Gulch and the river. The Shandon placers are in an area of several-square miles between the foot of the western escarpment of the Sierra Caballos and the Rio Grande at Shandon, and are located chiefly along Trujillo Gulch and its tributaries. Trujillo Gulch is a small, usually dry channel, which heads on the granite pediment at the foot of the mountains and drains due west to the river. Apache Canyon is a much larger valley opening out of the range from the east; it has formed along the course of a pronounced cross-fault. (See Plate I and figure 19.) Gold has been found in two places in Apache Canyon, the first discovery being in Union Gulch, a small gulch which leads out from the upper drainage basin of Trujillo Gulch. The second discovery was made in the summer of 1931, at a point in the main Apache Can- yon just below where it empties out onto the alluvial apron which forms the side of the valley. These discoveries have not proved to be important.
GEOLOGY
The Caballos escarpment is a prominent feature of the
topography in this part of the range, and the pre-Cambrian gran-
68Johnston, W. D., Jr., Fluorspar in New Mexico: N. Mex. Sch. of Mines, State Bur. of Mines and Min. Res. Bull. 4, 1928.