17 pcs 31.25 ct ROSASITE – MEXICO

Rosasite Rosasite is a gemstone that brings the vivid, electric colors of a tropical lagoon into the mineral cabinet. A copper zinc carbonate, it typically forms in beautiful, velvety mammillary crusts or tiny, radiating fibrous spheres. I have always been captivated by its specific shade of blue-green—a bright, "swimming pool" cyan that stands out even among other copper minerals. It is a secondary mineral, usually found in the oxidation zones of copper-lead-zinc deposits, where it grows in the quiet hollows of the rock. While it is too soft and fibrous for traditional faceting, I find that a high-quality specimen of Rosasite, with its silky luster and botryoidal form, possesses a decorative power that rivals any polished gem. It is a stone of vibrant energy and structural delicacy, representing the colorful "bloom" of metallic ores. The Heritage & Discovery Historical Significance: Rosasite is a classic indicator of the chemical transition between copper and zinc in an oxidized environment. Historically, it was often overlooked or confused with Aurichalcite, but its distinct density and crystal habit eventually set it apart. It represents a specific geochemical moment where copper and zinc ions are present in nearly equal measure. In the world of fine minerals, it is celebrated for its "fuzzy" or "velvety" appearance, standing as a favorite for collectors of secondary minerals. It serves as a beautiful reminder of how the harsh, metallic veins of the earth can transform into soft, colorful, and organic-looking structures when exposed to the elements near the surface. Discovery: The mineral was first described in 1908 and was named after its type-locality: the Rosas Mine in Narcao, Sardinia, Italy. This historic mine provided the first well-studied specimens of this beautiful carbonate, and the name has since become synonymous with high-quality blue-green botryoidal crusts worldwide. Important Mines: While Sardinia holds the historical title, some of the most spectacular, vibrant blue Rosasite specimens have come from the Ojuela Mine in Mapimí, Mexico, and the Tsumeb Mine in Namibia. I also have a high regard for the material found in the 79 Mine in Arizona, USA. For the vault, I prioritize the Mexican and Namibian specimens, as they often produce the most saturated "neon" blues and the most well-defined, velvety spheres that collectors find so irresistible. Mineralogical Profile Description: Rosasite is a copper zinc carbonate hydroxide that crystallizes in the monoclinic system. It sits at a 4 on the Mohs scale, making it a delicate mineral that should be handled with care and protected from abrasion. It is characterized by its vitreous, silky, or dull luster and its striking blue to green-blue color. One of its most identifying traits is its habit—it almost always forms as crusts, botryoidal (grape-like) masses, or radiating fibrous aggregates. It is often found in close association with other colorful minerals like blue Hemimorphite or green Conichalcite, creating spectacular multi-colored "vugs." Because it is a carbonate, it will effervesce (fizz) when exposed to warm dilute hydrochloric acid. It has a high refractive index ($n \approx 1.67$ to $1.83$), which contributes to the bright "snap" of its color. When I select a piece for the collection, I look for "undamaged velvet"—specimens where the tiny, fibrous crystals are perfectly intact, reflecting the light in a soft, shimmering sheen that defines the species. Chemical Formula: (Cu,Zn)₂(CO₃)(OH)₂