Copper

specimen number:
2102410

location:
Ray Mine, Pinal Co., Arizona, USA

description:
An attractive large crystallized grouping of native copper. Minor attached brecciated matrix. This is in terrific condition.

The Ray mine, located near Mineral Creek in Pinal County, Arizona, is a massive, world-class porphyry copper open-pit mining operation. Geologically, the deposit is centered on a complex of Laramide-aged igneous intrusions, primarily the Granite Mountain Porphyry, which penetrated Proterozoic sedimentary and metamorphic rocks around sixty million years ago. Intense hydrothermal alteration fractured the host rocks and deposited widespread, low-grade copper mineralization, which subsequently underwent profound supergene enrichment to form thick, blanket-like zones of high-grade copper oxides and sulfides, including chalcocite, chalcopyrite, chrysocolla, and native copper. Organized underground mining began at the site in 1911 under the Ray Consolidated Copper Company, utilizing early bulk-tonnage block-caving methods. The operation underwent a major technological transition between 1948 and 1955, phasing out underground shafts entirely in favor of a massive, continuous open-pit quarrying system. The mine has operated continuously for well over a century, passing through various corporate owners including Kennecott and Asarco, and it remains a highly active, high-volume producer of industrial copper today.

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