394 TECTONICS/Hydrothermal Vents At Mid-Ocean Ridges Table Minerals occurring in ocean ridge hydrothermal mineral deposits Table Ranges of elemental compositions in bulk mid ocean ridge hydrothermal mineral deposits Mineral group/name Element Sulphides/sulphosalts Most abundant Sphalerite Wurtzite Pyrite Chalcopyrite Less abundant Iss (isocubanite)a Marcasite Melnikovite Pyrrhotite Bornite chalcocite Covellite Digenite Idaite Galena Jordanite Tennantite Valeriite Sulphates Anhydrite Gypsum Barite Caminite Jarosite natrojarosite Chalcanthite Carbonates Magnesite Calcite Aragonite Elements Sulphur Oxides/hydroxides Goethite Lepidocrocite Hematite Magnetite Brucite Amorphous Fe compounds Amorphous Mn compounds Psilomelane Silicates Opaline silica Quartz Talc Nontronite Illite smectite Aluminosilicate colloid Hydroxychlorides Atacamite Chemical formula Zn(Fe)S Zn(Fe)S FeS2 CuFeS2 Variable (CuFe2S3) FeS2 FeS2-x Fe1-x S Cu5FeS4 Cu2S CuS Cu9S5 Cu5 5FeS6 PbS Pb9As4S15 (Cu,Ag)10(Fe,Zn,Cu)2As4S23 2(Cu,Fe)2S23(Mg,Al)(OH)2 CaSO4 CaSO4 H2O BaSO4 MgSO4 xMg(OH)2 (1 2x)H2O (K,Na)Fe3(SO4)2(OH)6 CuSO4 5H2O MgCO3 CaCO3 CaCO3 S FeO(OH) FeO(OH) Fe2O3 Fe3O4 Mg(OH)2 (Ba,H2O)2Mn5O10 SiO2 nH2O SiO2 Mg3Si4O10(OH)2 (Fe,Al,Mg)2(Si3 66Al0 34)O10(OH)2 Cu2Cl(OH)3 a Iss, Intermediate solid solution mineral structures and from the thermal and chemical gradients across mineral structures The structures provide an interface between seawater and hydrothermal fluid that maintains tolerable temperatures for biota, and allows organisms simultaneous access to the chemical constituents in both seawater and Cu Fe Zn Pb S SiO2 Ba Ca Au Ag As Sb Co Se Ni Cd Mo Mn Sr Rangea 0.1 15.0 wt.% 2.0 44.0 wt.%