New Mexico Mineral Symposium — Abstracts

The Alhambra mine is located in the Blackhawk district, which lies in the Big Burro Mountains of western Grant County. The minerals of the Alhambra mine form an assemblage that is unique not only to New Mexico but to the United States as well. Initially located by the discovery of silver float in 1881, mining in the district ceased by 1893 due to a decrease in the price of silver. Since that time exploratory, developmental, and mining efforts have been sporadic with negligible silver production.

The Blackhawk district is within the Precambrian Burro Moun-tains batholith, which is composed primarily of granite with inclusions of gneiss, schist, and quartzite. Many stocks and dikes intrude the batholith. The primary ore-producing vein at the Alhambra mine cuts through quartz diorite gneiss near a large easterly trending monzonite porphyry dike.

The minerals to be discussed were found on the dumps of the Alhambra mine and in stockpiles produced during mining operations that were conducted during the autumn of 1979. Of particular interest at the Alhambra mine is the occurrence of nickel¬-skutterudite, because the Blackhawk district is the type location for this rare species. Additional species of interest include silver, acanthite, niccolite, erythrite, annabergite, "pitchblende" plus the more common sulfides, and a suite of interesting carbonate gangue minerals.