Hillsboro Placer District — Sierra County

McLemore (1994) lists Hillsboro among 36 New Mexico mining districts containing placer gold (NMBGMR Resource Map 24, district DIS197). Estimated placer production: approximately 120,000 ounces of historical placer gold from 1828–1991 statewide context (662,000 oz total NM placer production). Production period: 1877-1982. District cumulative production (all commodities): $8,500,000. Deposit types: carbonate-hosted manganese replacement, carbonate-hosted Pb-Zn (Cu, Ag) replacment, carbonate-hosted silver-manganese (Pb) replacement, Laramide skarn, polymetallic vein, placer gold, porphyry copper. Also known as: Las Animas, Copper Flat, Hillsborough, Wicks Gulch. Copper Flat (NMSI0610) has 113 million short tons at 0.30% Cu, 0.009% Mo, .096 g/t Au, and 1.93 g/t Ag (NI43-101 reserves). Copper Flat deposit is not to be confused with the Copper Flat district in Grant County. Placer gold occurs as native gold and electrum in incised valleys and alluvial fans. Most economic placers were discovered by 1900; recreational panning may find fine colors — verify land status before prospecting. Coordinates approximate the district centroid from NMBGMR Resource Map 24 GIS (DIS197).