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Table 2 Dissolution reactions considered in the model

From: The element-release mechanisms of two pyrite-bearing siliciclastic rocks from the North German Basin at temperatures up to 90 °C under oxic and anoxic conditions

Phase Reaction Log K ∆H (KJ/mol)
Amorphous silica SiO2(am) ↔ SiO2(aq) − 2.71 20.05
Kaolinite Al2Si2O5(OH)4 + 6H+ ↔ 2Al3+ + 2SiO2(aq) + 5H2O 6.81 − 151.8
Muscovite KAl3Si3O10(OH)2 + 10H+ ↔ 3Al3+ + K+ + 3SiO2(aq) + 6H2O 13.6 − 243.2
Calcite CaCO3 + H+ ↔ Ca2+ + HCO 3 1.85 − 25.71
Pyrite FeS2 + 3.5O2 + H2O ↔ Fe2+ + 2SO 2−4  + 2H+ 217.4 − 1412
FeS2 + 14Fe3+ + 8H2O ↔ 15Fe2+ + 2SO 2−4  + 16H+ 98.5 − 50.69
Ferrihydrite Fe(OH)3 + 3H+ ↔ Fe3+ + 3H2O 2.54 − 84.08
Amorphous aluminum hydroxide Al(OH)3 + 3H+ ↔ Al3+ + 3H2O 9.7
Manganese oxo-hydroxide MnOOH + 3H+ ↔ Mn3+ + 2H2O − 0.16
  1. Data taken from the LLNL database, except log K of ferrihydrite (SIT database) and amorphous aluminum hydroxide (Kittrick 1969). Values for the standard enthalpy of formation ΔH for amorphous aluminum hydroxide and manganese oxohydroxide are not available in the databases