Pearceite is an uncommon mineral containing silver and copper in its structure. It forms a series with Polybasite, with Pearceite being the arsenic-rich member and Polybasite being the antimony-rich member. It is often not possible to visually distinguish these two minerals from each other. Pearceite is named in honor of Dr. Richard Pearce (1837-1927), a Cornish-American chemist from Colorado.
Pearceite is not a common mineral. Worldwide localities include Měděnec, Chomutov District, Bohemia, Czech Republic; the Uchucchacua Mine, Oyon Province, Lima Department, Peru; and the San Juan de Rayas Mine, Guanajuato, Mexico. In the U.S., Pearceite has come from the Mollie Gibson Mine, Aspen, Pitkin County, Colorado; and from Neihart, Cascade Co., Montana.
