Brochantite with Cyanotrichite

specimen number:
2262052

location:
Vieja Mine, Potrerillos, Chanaral, Atacama, Chile

description:

Green micro crystals of brochantite throughout this matrix with blue micro crystallized cyanotrichite.

The La Vieja Mine, located in the Potrerillos District of the Chanaral Province, Atacama, Chile, is a classic locality known for its diverse suite of secondary copper and arsenic minerals. Geologically, the deposit is part of the extensive Andean porphyry copper belt, where Mesozoic and Cenozoic magmatic activity intruded into Paleozoic basement rocks, leading to the formation of rich oxide and supergene enrichment zones. The mine is particularly noted by collectors for producing sharp crystals of powellite, brochantite, and cyanotrichite, along with rare arsenates like olivenite and clinoclase. Historically, the mine operated as part of the broader Potrerillos mining complex, which saw significant industrial development and production from the early 1920s through the mid-20th century under the Andes Copper Mining Company. While primary production focused on large-scale copper extraction for the Potrerillos smelter, La Vieja gained a distinct reputation among mineralogists for the high quality of its micro-minerals and rare species found in the oxidized portions of the ore body. Today, while the original workings are largely inactive or integrated into larger regional operations, specimens from La Vieja remain important reference materials for the complex mineralogy of the Chilean Atacama Desert.

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