Use this geological calculation for a transparent first-pass interpretation of measured rock, soil, fluid, well, stratigraphic, isotopic, geophysical, or seismic data under an explicitly selected model.

FeO

FeO weight percent.

Fe2O3

Fe2O3 weight percent, recalculated to FeO.

MgO

MgO weight percent.

Na2O

Na2O weight percent.

K2O

K2O weight percent.

Convert whole-rock oxides to AFM coordinates with ferric iron recalculated to FeO for the tholeiitic-calc-alkaline AFM triangle. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

FeO total

Total iron expressed as FeO.

A %

(Na2O+K2O) apex percent of the AFM sum.

F %

FeO total apex percent.

M %

MgO apex percent.

• Geological models are scale-, site-, method-, and calibration-dependent. Heterogeneity, anisotropy, sampling, diagenesis, pressure-temperature history, instrument response, boundary conditions, and empirical-correlation range can dominate the result.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Compare independent measurements and models, retain units and analytical metadata, propagate uncertainty, and validate interpretations against logs, cores, maps, laboratory data, or field observations.

• Mg Number Vs Silica Calculator

  Compute the molar Mg number (100*Mg/(Mg+Fe)) with ferric iron converted to ferrous, paired with SiO2 for differentiation-trend plots.

• QAPF Plot Calculator

  Normalize modal quartz, alkali feldspar, plagioclase and feldspathoid contents to QAPF coordinates and pick the plotting triangle.

• TAS Diagram Plot Calculator

  Prepare total-alkalis versus silica coordinates and the Le Bas silica band for plotting on the IUGS TAS diagram.