In terrestrial rocks, Br minerals are extremely rare with only nine minerals known where Br is a dominant component. A new arsenite bromide mineral ermakovite, (NH 4 )(As 2 O 3 ) 2 Br, was discovered at the tract of Kukhi-Malik, Fan-Yagnob coal deposit, ca. 75 km N of Dushanbe, Tajikistan. Ermakovite is a fumarolic mineral formed directly from gas from a natural underground coal fire. Associated minerals are sulfur, realgar, amorphous As-sulfides, salammoniac, alacranite,