Page 165 - The Geology and Ore Deposits of Sierra County, New Mexico - Bulletin 10

MINING DISTRICTS 163
crosscutting in both directions until all of the 12 parallel veins reported to be present in this area were intersected.
The old camp of Andrews and the neighboring Tripp, Homestake, Freidberg, Buetecke, and other mines, in effect the entire northeast portion of the Hillsboro district north of Copper Flat, produced, according to several independently obtained esti- mates, only about $260,000 in net smelter and bullion returns up to 1904, when most of the mines in the region became idle. Al- lowing $25,000 to take care of miscellaneous shipments not in- cluded in the above estimate and all minor shipments made sub- sequently, a total of $285,000 seems to be about the maximum production from this part of the district to date. For many years prior to the organization of the present company the El Oro mines were under water, but these workings were pumped out early in 1932, and operations were resumed. It is under- stood that at least twice since that time the mine has been al- lowed to fill up again during temporary shutdowns.
The writer made one visit underground in August, 1932, seeing all workings in the Golden Rule Shaft No. 2, except on one level which was said to be caved, and all the workings in the New El Oro shaft, which included a 500-foot shaft, a northwest crosscut over 40 feet in length, and a southeast crosscut which was over 90 feet in length. Based on these observations the opinion is offered that the surface plant and improvements in progress were larger than justified and that they represented an ill- advised expenditure of money in view of the very small amount of ore actually blocked out in the mine.
The exposed ore bodies in the workings from the Golden Rule Shaft No. 2 and the El Oro shaft were not sampled by the writer, but the mineralization appears to be weak. The geological features, the character of the mineralization, and the results obtained from past mining operations are not encouraging for the existence of large and profitable ore bodies in this area. Some of the recently acquired properties, particularly the Richmond mine (see pages 145-148) are more promising than the El Oro mine proper.
COPPER FLAT CLAIMS
The mineralized area in Copper Flat is held by 20 full-sized
mining claims, of which six are patented. This property is owned by Max Hiltscher, for many years a resident of the Hills- boro district.
The area consists primarily of a cupola of monzonite por- phyry, which forms the floor of the basin and is in irregular con- tact with the main andesite country rock of the district on all sides, as shown on Plate VI. The southern end of this mass was apparently more resistant to erosion, as it remains within the basin as a group of low, rounded hills. These hills are composed of a finer grained phase of the monzonite porphyry, which is almost aphanitic in places, and it is believed that they are rem-