Table 1 Chemistry used in selected synthesis experimentsa

From: Clay mineral formation under oxidized conditions and implications for paleoenvironments and organic preservation on Mars

  100-Fe Controlb 100-Fe3+ 5-Mg 95-Fe3+ 15-Mg 85-Fe3+ 50-Mg 50-Fe3+ 100-Mg
Chemical Name Amount Cation (mol) Amount Cation (mol) Amount Cation (mol) Amount Cation (mol) Amount Cation (mol) Amount Cation (mol)
Sodium metasilicate—pentahydrate 0.0204 0.0204 0.0204 0.0205 0.0204 0.0205
Iron (II) sulfate—heptahydrate 0.0142
Sodium dithionite 0.0241
Iron (III) sulfate—rhomboclase & ferricopiapite 0.0138c 0.0146c 0.0117c 0.0069 c
Magnesium sulfate—epsomite 0.0007 0.0022 0.0071 0.0142
Fe:Mg ratio 1:0 1:0 19:1 17:3 1:1 0:1
  1. All experiments were aged for 1 day at room temperature and then heated for an additional 2 days at 150 °C—for experiments incubated at 100 °C for 60 days see methods
  2. aFor all experimental conditions see Supplementary Tables 1 and 2
  3. b100-Fe bearing control condition, which was synthesized from initially ferrous Fe-containing solutions (sodium dithionite was added to maintain reducing conditions for the ferrous Fe) and then oxidized using published methods9
  4. cFe(III) molar concentrations were determined by atomic absorption spectroscopy
Solution name Amount (mL) Amount (mL) Amount (mL) Amount (mL) Amount (mL) Amount (mL)
Sodium hydroxide (5 M) 19.80 19.80 19.80 19.80 19.80 19.80
H2O 417.52 419.96 417.11 416.41 417.11 417.87
Sulfuric acid (0.5 M) 41.00 42.00 42.00 42.00 42.00 42.00
Ending pH 12.49 12.69 12.64 12.76 12.79 12.88
  1. All experiments were aged for 1 day at room temperature and then heated for an additional 2 days at 150 °C—for experiments incubated at 100 °C for 60 days see methods
  2. aFor all experimental conditions see Supplementary Tables 1 and 2
  3. b100-Fe bearing control condition, which was synthesized from initially ferrous Fe-containing solutions (sodium dithionite was added to maintain reducing conditions for the ferrous Fe) and then oxidized using published methods9
  4. cFe(III) molar concentrations were determined by atomic absorption spectroscopy