Mining history of the Carthage coal field, Socorro County, New Mexico
— Gretchen K. Hoffman and Joseph P. Hereford

The Carthage coal field in east-central Socorro County lies on the east flank of the Rio Grande Rift in a series of small fault blocks which contain the coal-bearing units. The Tres Hermanos and Crevasse Canyon Formations coal-bearing sequences both outcrop in the field but only the Crevasse Canyon has coal of minable thickness. This unit contains two coal seams ranging in thickness from 4 to 7 ft. The lower bed, called the Carthage seam, is the main source of coal extracted in the field, beginning in the 1860s. This seam is an excellent coking coal and relatively high in Btu value (12,531 Btu/lb). The proximity to southwest smelters in the 1880s and development of a rail spur connecting to the main line created the first surge of coal
mining activity in the Carthage field. Carthage would experience several pulses of coal development until the late 1960s. Over 2 million short tons (st) of coal were produced from mines within the Carthage field from 1882-1963. The majority of the easily mined coal has been extracted from this field and the structure of the field does not lend itself to today’s large-scale mining.