the rare bismuthide maldonite (Au 2 Bi) and antimonide aurostibite (AuSb 2 ). Gold also occurs in rare alloys with copper , lead , and mercury : the minerals auricupride (Cu 3 Au), novodneprite (AuPb 3 ) and weishanite ((Au, Ag) 3 Hg 2 ). Recent research suggests that microbes can