Brochantite

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Green prismatic terminated crystals of brochantite on matrix. In good condition.The Milpillas Mine, located in the Cuitaca District near Santa Cruz, Sonora, Mexico, is a modern underground copper operation that gained worldwide fame for its extraordinary secondary mineral specimens. Geologically, it is a high-grade porphyry copper deposit where the primary mineralization was subjected to intense supergene enrichment. This process occurred as meteoric waters leached copper from upper layers and redeposited it in lower oxidation zones, creating spectacular pockets of carbonates and sulfates. Historically, the mine was developed by Industrias Penoles and began commercial production in 2006. While it was built as an industrial copper mine, it became legendary among collectors for producing the world's finest brochantite crystals. These specimens feature deep emerald-green, lustrous, and elongated prismatic crystals that often exceed the quality of any other known locality. Although the most famous mineral pockets were encountered between 2006 and 2015, the mine remains an important industrial site, with its specimens preserved in major museums and private collections globally as benchmarks for the species.