Rhodochrosite

specimen number:
1052766

location:
Eagle Mine, Bonanza, Saguache Co., Colorado, USA

description:
Pink crystallized rhombohedral rhodochrosite in open pockets throughout a massive rhodochrosite matrix. In good condition. Interesting old timer, this comes with an antique label that dates the piece to 1908.

The Eagle mine, situated in the high-altitude Bonanza mining district within the Kerber Creek basin of Saguache County, Colorado, was a significant producer of base and precious metals. Geologically, the deposit sits within the Bonanza caldera, a major Oligocene-age volcanic collapse structure where thick sequences of andesitic and rhyolitic lava flows were intensively faulted and fractured. Hydrothermal solutions originating from deep-seated magmatic activity filled these fault fissures, creating prominent epithermal veins rich in argentiferous galena, sphalerite, chalcopyrite, and tennantite, hosted in a quartz and rhodochrosite gangue. Historically, prospecting in the area picked up following the 1880 Bonanza silver rush, leading to the development of the Eagle vein through underground adits and shafts. The mine experienced its primary eras of industrial corporate activity from the late 1890s through the 1920s, with a major production resurgence occurring during the 1940s and 1950s when the raw base metals were heavily sought after for industrial use. Due to the eventual depletion of the high-grade silver-lead ore shoots and unfeasible deep operating costs in the complex volcanic terrain, organized commercial mining operations at the Eagle property steadily declined, culminating in the permanent abandonment of the underground workings by the mid-1960s.

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