Since argentite (Ag 2 S) is isomorphous with galena, it is probable that the silver isomorphously replaces lead, but it is to be noted that native silver has been detected as an enclosure in galena.
The galena group includes several other cubic minerals, such as argentite (q.v.).
Silver sulphide, Ag 2 S, occurs naturally as the orthorhombic acanthite, and the cubic argentite; the telluride, Ag 2 Te, named hessite, assumes cubic forms; other tellurides containing silver are petzite, (Ag,Au) 2 Te, and sylvanite, AuAgTe 4.
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.
In amalgamating without the use of chemicals, finely divided iron, worn from the shoes and dies in the stamp-mill and the pan, decomposes cerargyrite and argentite, and the liberated silver is taken up by the quicksilver; the process is hastened by adding salt.
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.
Silver sulphide, Ag 2 S, constitutes the mineral argentite or silver glance, and may be obtained by heating silver with sulphur, or by precipitating a silver salt with sulphuretted hydrogen.