csa08

I just have a quick question regarding the molar volume in 'thermo.dat' of the jarosites I have coppied and pasted the values: Jarosite-K type= sulfate formula= KFe3(SO4)2(OH)6 mole vol.= 153.200 cc mole wt.= 500.7983 g 5 species in reaction 2.000 SO4-- 3.000 Fe+++ 6.000 H2O 1.000 K+ -6.000 H+ -5.8197 -8.8889 -12.4748 -15.7308 -18.9953 -21.8913 500.0000 500.0000 Jarosite-Na type= sulfate formula= NaFe3(SO4)2(OH)6 mole vol.= 469.050 cc mole wt.= 484.6898 g 5 species in reaction 2.000 SO4-- 3.000 Fe+++ 6.000 H2O 1.000 Na+ -6.000 H+ -4.8714 -4.8714 500.0000 500.0000 500.0000 500.0000 500.0000 500.0000 My question is how would one obtain a Jar-Na mol vol of 469.050 cc? while Jar-K is 153.200 cc and they are roughly the same mol wt and density. I am also trying to add schwertmannite to this dataset if anyone knows of thermo data that contains it - I am using GWB v6. Thankyou! AJ