Brochantite

specimen number:
2072219

location:
Milpillas Mine, Sonora, Mexico

description:
Choice needlelike crystals of emerald green brochantite coming off matrix. In good condition. Choice thumbnail for the species.

The Milpillas Mine, located in the Cuitaca District of Santa Cruz, Sonora, Mexico, is a world-class copper deposit situated within the Laramide porphyry copper province. Geologically, it is a high-grade supergene enrichment zone buried beneath several hundred meters of post-mineralization gravels, where primary copper sulfides were oxidized to form spectacular secondary minerals. The mine is famous for producing what are considered the finest brochantite crystals in the world, which occur as deep emerald-green, lustrous, elongated prisms and acicular sprays, often found in association with vibrant blue azurite and malachite. Historically, the deposit was discovered in the late 20th century through sophisticated geophysical prospecting, and industrial underground mining commenced in 2006 under the operation of Industrias Penoles. Throughout its primary production years until the late 2010s, the mine became a legendary source for collectors due to the careful hand-recovery of mineral specimens during the extraction of copper ore. While mining focus has shifted over time, the Milpillas brochantites remain the gold standard for the species, prized for their exceptional size, color, and transparency.

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