Bulletin 86—Geology and ore deposits of the Sacramento (High Rolls) mining district, Otero County, New Mexico

By S. E. Jerome, D. D. Campbell, J. S. Wright, and H. E. Vitz, 1965, 30 pp, 1 table, 18 plates.

In the Sacramento mining district, Otero County, NM, the Permian Abo Formation unconformably overlies folded and faulted rocks of pre-Permian age; in turn, it is overlain conformably by the Permian Yeso Formation. Structure in the Abo and Yeso is relatively simple, being generally a monocline striking north and dipping gently east and cut by faults of moderate throw. The few intrusives in the district are sills of andesite with no associated mineralization or alteration.

The Abo contains small, irregular deposits of copper and lead minerals occurring separately or associated in discontinuous, light-colored arkose beds sandwiched between red shales. Total production from these deposits through 1962 probably does not exceed 23,000 tons of lead ore varying between 5–11% lead and 6,500 tons of copper ore varying between 2–7% copper. Minor amounts of other metals occur with these principal ore types.

Evidence accumulated as a result of surface and underground mapping, a large number of assays, and extensive testing of favorable-appearing arkose beds with acetic acid and potassium iodide for lead sulfate and lead carbonate strongly suggests that the ores are semisyngenetic in origin. Copper and lead sulfides were possibly deposited with the arkose. The source of the metals has not been established. Both copper and lead sulfides were later oxidized and the metals reconcentrated to some extent as carbonates and sulfates by the action of ground water. Provided such an origin is correct, the overlying Yeso Formation and the underlying rock units, predominantly the Magdalena Group, contain no ore deposits that are genetically related to those in the Abo.

The Sacramento district is on the western slope of the Sacramento Mountains, east of Alamogordo, in the north-central part of Otero County, NM. The district is considered to extend from Red Hill, half a mile north of High Rolls, to Alamo Canyon, seven mi due south of High Rolls. A well-maintained forest road, locally known as the West Side Road, branches from State Highway 83 near High Rolls and provides access to much of the region.

Vegetation includes ponderosa pine, piñon, juniper, scrub cedar, and scrub oak of several types liberally interspersed on the lower sunny slopes with a wide variety of spiny desert plants. Excellent fruit is grown in the vicinity of High Rolls.

Elevations in the district range between 6,500 ft and 7,500 ft, while those of the Sacramento Mountains as a whole range from 4,200 ft at the western mountain front in the Tularosa Basin to 9,500 ft at the crest. This relief of 5,300 ft makes for considerable variety in the climate. Summers are hot and are characterized by sudden showers; cold and snow or rain can extend over several months during the winter season.