Antimony, however, occurs chiefly as the sulphide, stibnite; to a much smaller extent it occurs in combination with other metallic sulphides in the minerals wolfsbergite, boulangerite, bournonite, pyrargyrite, &c. For the preparation of metallic antimony the crude stibnite is first liquated, to free it from earthy and siliceous matter, and is then roasted in order to convert it into oxide.
This is illustrated by the hexagonal pyrargyrite 3Ag 2 S Sb 2 S 3, and proustite, 3Ag 2 S As2S3, and the monoclinic pyrostilpnite, isomeric with pyrargyrite, and xanthoconite, isomeric with proustite.
The leading silver minerals are native silver; argentite or silver glance, Ag 2 S, usually containing small amounts of lead, copper and tin; dyscrasite or antimonial silver, Ag 2 Sb to Ag,3Sb, an isomorphous mixture of silver and antimony; proustite or light red silver ore, Ag 3 AsS 3; pyrargyrite or dark red silver ore, Ag 3 SbS 3; stephanite, Ag 5 SbS 4; miargyrite, AgSbS2; stromeyerite, CuAgS; polybasite, 9(Cu 2 S,Ag 2 S) (Sb 2 S 3, As 2 S 3); cerargyrite or horn silver, AgCI; bromite or bromargyrite, AgBr; embolite, Ag(C1,Br); iodite or iodargyrite, AgI.
Cupric chloride acts upon argentite (Ag2S+ CuC1 2 =2AgC1+CuS), proustite (4Ag 3 AsS 3 +4CuC1 2 =8AgC1-}- 2Ag 2 S+4CuS+2As 2 S 3), pyrargyrite (2Ag 3 SbS 3 -I-3CuC1 2 =6AgC1+ 3CuS+Sb 2 S 3), and is also reduced to cuprous chloride by metallic iron.
This salt, insoluble in water but soluble in brine, also acts upon argentite (Ag 2 S-+-Cu 2 C1 2 =2AgC1±-CuS±-Cu) and pyrargyrite (2Ag 3 SbS 3 -I-Cu 2 C12 = 2AgC1 +Ag 2 S +2Ag +2CuS +Sb2S3), and would give with silver sulphide in the presence of quicksilver, the Patioreaction; metallic silver, cupric sulphide, and mercurous chloride (2Ag 2 S+Cu 2 C1 2 +2Hg=4Ag+2CuS+Hg 2 C1 2), but the iron decomposes the quicksilver salt, setting free the quicksilver.