Formulation

Calculations outline:

 Method Example oxide name from data SiO2 weight% from data 43.5% mol wt. from periodic table 60.02 mol prop. (weight%) / (mol wt.) .7248 cation prop (mol prop.) x (# cations in oxide) .7248 oxygen prop. (mol prop.) x (#oxygen in oxide) 1.4496 cations on basis of # of O (e.g., 12) (correction factor**) x (cation prop.) (e.g., for a correction factor = 1.699) 1.231 cation assignment from radius ratio 4 CN

**Correction factor = (# of oxygens in ideal formula) / (sum of oxygen props.)

*Remember to check for electroneutrality

Formulation example:

Mineral: Olivine - ideal formula (Fe,Mg)2SiO4

 OxideName SiO2 FeO MnO MgO Total WeightPercent 34.96 36.77 0.52 27.04 99.29 Mol. Prop. 0.5818 0.5118 0.0073 0/6708 Cation Prop. 0.5818 0.5118 0.0073 0.6708 OxygenProp. 1.1636 0.5118 0.0073 0.6708 2.3535 **Cats onbasis of 4 0.989 0.870 0.012 1.140 CN Site 4 CN 6 CN 6 CN 6 CN

**Correction factor = (# of oxygens in ideal formula) / (sum of oxygen props.)
e.g., for olivine: # of oxygen in ideal formula = 4
in the table above, the sum of the oxygen proportions for all of the oxides came to 2.3535

Then the correction factor would be (4) / (2.3535) = 1.699

The composition of the above olivine would then be:

(Mg1.14Fe0.87Mn0.01)Si0.99O4