2.1" Manganoan Adamite and Austinite Association - Ojuela Mine, Mexico

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 well-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.

Austinite is a member of the adelite-descloizite group and has the chemical formula CaZn(AsO4)(OH). It forms in oxidized arsenic-rich metal deposits and is often associated with adamite, limonite, talmessite, and quartz. It often exhibits a greenish coloration, though it has also been known to occur as yellow, brown, white and yellow-white aggregations. Austinite has been collected from the United States, Mexico, Australia, Bolivia, Namibia and several other locations.

Austinite was named after Austin Flint Rodgers, an American mineralogist at Stanford University.