Pearceite

Pearceite is one of the four so-called "ruby silvers", pearceite Cu(Ag,Cu)₆Ag₉As₂S₁₁, pyrargyrite Ag₃SbS₃, proustite Ag₃AsS₃ and miargyrite AgSbS₂. It was discovered in 1896 and named after Dr Richard Pearce (1837–1927), a Cornish–American chemist and metallurgist from Denver, Colorado.