Gemmy, Purple Adamite & Calcite Association - Durango, Mexico
This is a beautiful specimen of gemmy, purple adamite crystals associated with small calcite crystals, collected from the Ojuela Mine in Durango, Mexico. Most of which formed in a druzy fashion atop a limonitic matrix. The purple adamite is in a small geodic cavity along one side of the specimen.
Adamite is a basic zinc arsenate with the base chemical formula of Zn2(AsO4)(OH). When impurities are present in the mineral, the color is altered, explaining the wide variety of colors that adamite displays. Copper and Cobalt are some of the known impurities that can give mineral specimens a green (Cu) to pink/red (Co) color. Adamite is typically found imbedded in a limonite matrix, formed as a secondary mineral in oxidation zones of hydrothermal replacement deposits.