| comments are preceded by the "|" character

NIL16_MC_fit_option.dat     | the MC_fit_option file name

begin_assemblage            | this tag signals the beginning of the problem definition

sample_name NIL_16-1        | Samuel et al, J Pet 60:1027-1062, 2.5 log units above QFM, 650-800 C, 700-1100 MPa

pressure_range 8000 18000   | bar, pressure range of initial guesses

temperature_range 950 1350  | K, temperature range of initial guesses

unmeasured_component O2

begin_limits
                            | Limit expressions are in molar units regardless of whether 
                            | "molar" or "mass" is specified in section 1.

                            | This is a coupled limit, i.e., the limit on the 
                            | unmeasured component is function of the amounts 
                            | of other components (here FeO)

                            | stoichiometric factors after the component name
                            | express min/max limits on the unmeasured component
                            | in terms of the specified component, e.g. , here
FeO   0   0.125             |          molar O2 >= 0 
                            |          molar O2 <= 1/4 molar FeO
                            | 100% ferric iron requires O2 = 1/4 FeO, therefore
                            | the range here implies ferric-ferrous ratios in the range [0,1] 
end_limits

| The coexisting phases, modes (optionally) and their compositions follow 
| and must be terminated by the end_assemblage tag. Only one assemblage can be 
| analyzed per MC_Fit calculation. Text (e.g., data for additional assemblages, 
| comments, notes) entered after the end_assemblage keyword is NOT read by MC_Fit.

| Phase names used here must correspond to the solution models specified in
| the problem definition file or to endmember names in the thermodynamic data
| file specified in that file.

phase_name Cpx(HGP)

| Component names used here must match those specified in the problem 
| definition file. If the phase is an endmember its composition is not
| read. 

| !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
| The compositions here are MASS fractions and the uncertainties are 
| absolute errors, the MC_fit options molar_composition_input and 
| relative_error must be set accordingly
| !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

begin_comp
SiO2    49.76   0.44
TiO2     0.47   0.05
Al2O3    4.64   0.27
Cr2O3    0.09   0.02
FeO      9.41   0.40
MgO     12.39   0.19
CaO     22.30   0.40
Na2O     0.84   0.05
end_comp

phase_name Gt(HGP)

begin_comp
SiO2     38.89   0.47
TiO2      0.06   0.05
Al2O3    21.69   0.14
Cr2O3     0.10   0.02
FeO      24.51   0.30
MgO       8.38   0.23
CaO       6.88   0.46
end_comp

end_assemblage

| text after the end_assemblage tag is not read by MC_fit ...

NIL_16-1 sample (metagabbro) contains
q (scarce)
plg
ksp
cpx
gt
amph
hm-ilm
mt
(oxide rims on opx, cpx, hbd, no S)