Copper (Cu-039)

specimen number:
9273175

location:
Chino Mine, Grant Co., New Mexico

description:

A loose choice spinel law twin crystal grouping of native copper. In great condition.

The Chino mine, also known as the Santa Rita mine and located in Grant County, New Mexico, is an immense, active open-pit copper operation that ranks as one of the oldest industrial mining sites in North America. Geologically, it is a world-class porphyry copper deposit structurally centered on a highly altered Upper Cretaceous to Eocene quartz monzonite porphyry stock that intruded local Paleozoic and Mesozoic sedimentary strata. Hydrothermal fluids extensively fractured the rock, depositing primary chalcopyrite and bornite, which later underwent intense supergene enrichment to form high-grade blankets of secondary chalcocite, native copper, and various oxidized copper minerals. Native Americans and early Spanish explorers extracted native copper from the surface outcrops in the late 1700s, with formal underground and surface mining expanding throughout the nineteenth century. Large-scale, mechanized open-pit mining operations were initiated in 1910 by the Chino Copper Company and have run dynamically through various corporate mergers under Chino, Kennecott, Phelps Dodge, and Freeport-McMoRan, with production continuing actively today alongside major modern milling and SX-EW processing facilities.

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