TITLE Example 16.--Inverse modeling of Sierra springs
SOLUTION_SPREAD
        -units mmol/L
Number	pH	Si	Ca	Mg	Na	K	Alkalinity	S(6)	Cl
1	6.2	0.273	0.078	0.029	0.134	0.028	0.328      	0.01	0.014
2	6.8	0.41	0.26	0.071	0.259	0.04	0.895    	0.025	0.03

INVERSE_MODELING 1
        -solutions 1 2
        -uncertainty 0.025
        -range
        -phases
                Halite
                Gypsum
                Kaolinite               precip
                Ca-montmorillonite      precip
                CO2(g)
                Calcite
                Chalcedony              precip
                Biotite                 dissolve
                Plagioclase             dissolve
        -balances
                Ca      0.05     0.025
PHASES
Biotite
        KMg3AlSi3O10(OH)2 + 6H+ + 4H2O = K+ + 3Mg+2 + Al(OH)4- + 3H4SiO4 
        log_k  0.0      # No log_k, Inverse modeling only
Plagioclase
        Na0.62Ca0.38Al1.38Si2.62O8 + 5.52 H+ + 2.48H2O = \
                0.62Na+ + 0.38Ca+2 + 1.38Al+3 + 2.62H4SiO4
        log_k  0.0      # No log_k, inverse modeling only
END