Atacamite

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Sparkling green radiating crystals of atacamite covering one side of matrix. In good condition. The La Farola mine, located in the Tierra Amarilla commune near Copiapo within the Atacama Region of Chile, is an iron oxide copper-gold (IOCG) deposit situated along the southern margin of the Candelaria-Punta del Cobre district. Geologically, the deposit is hosted along the structural contact between Lower Cretaceous andesitic volcanic flows of the Punta del Cobre Formation and overlying marine carbonates of the Chanarcillo Group, where syn-mineralization strike-slip faults acted as primary pathways for hydrothermal fluids to precipitate chalcopyrite, pyrite, and specular hematite. Small-scale artisanal miners and prospectors operated localized underground tunnels and open pits intermittently during the twentieth century, with targeted extraction of mineral specimens peaking from the 1990s through the 2010s. While a large-scale modern corporate open-pit copper project secured environmental approvals in April 2025 to begin development, independent local prospectors continue to surface-mine the historic vugs and fractures. Atacamite is a copper halide mineral forming primarily as a secondary mineral in the oxidized zones of copper ore bodies under hyperarid desert conditions. The mineral typically crystallizes as deep green, slender acicular needles, fibrous aggregates, or lustrous prismatic crystals that often grow as radiant sprays on contrasting matrices of chrysocolla or altered porphyry. Named after the Atacama Desert where it was originally discovered, the species requires an environment rich in chlorine and a high evaporation rate, making the hyperarid climate surrounding districts like La Farola ideal for producing some of the world's finest and most lustrous examples.