Rosasite

specimen number:
2102220

location:
Silver Bill Mine, Cochise Co., Arizona, USA

description:
Attractive velvety blue crystallized rosasite across the top of matrix. In good condition, nice for the species from this Arizona locality.

The Silver Bill Mine, located in the Turquoise District of the Dragoon Mountains in Cochise County, Arizona, is a historic operation famous for its colorful secondary lead and zinc minerals. Geologically, the deposit is a carbonate-replacement system where hydrothermal fluids related to nearby quartz monzonite porphyry intrusions reacted with the Mississippian Escabrosa Limestone. This process created irregular ore bodies and filled solution cavities with rich concentrations of silver-bearing galena, sphalerite, and copper ores. Over time, extensive oxidation of these primary sulfides produced a spectacular array of secondary species, most notably brilliant blue and green smithsonite, hemimorphite, aurichalcite, and its characteristic botryoidal velvety rosasite. Historically, the mine was first worked in the late 1870s and 1880s during the regional silver boom, with the most intensive periods of production occurring between 1890 and the late 1920s. While small-scale leasing and specimen recovery continued intermittently through the mid-20th century, the mine is now closed to commercial production. It remains a classic American locality, prized by mineralogists for the exceptional aesthetics and variety of its oxidized mineral specimens.

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