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Pyroxene Wo-En-Fs Calculator

Calculate pyroxene wollastonite–enstatite–ferrosilite (Wo–En–Fs) endmember proportions from Ca-Mg-Fe cations or oxides, with a ternary plot — a compositional representation, not a full classification.

100% FreeRuns in your browserIntermediate
How to use this calculator

Composition

Uses Ca–Mg–Fe²⁺ cation proportions. Do not use total Fe as Fe²⁺ without stating the assumption.

Wo–En–Fs

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More needed
  • Enter the component values.
Assumptions & basis
  • Basis: Cation proportions (a composition, not an identification) (derived)

Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.

How to use this calculator

  1. Enter Ca, Mg and Fe²⁺ as cations, or CaO, MgO and FeO as wt%.
  2. Read Wo, En and Fs percentages, the ternary point and the notation.

How it works

The pyroxene quadrilateral endmembers are the cation proportions normalised to 100%: Wo = Ca/(Ca+Mg+Fe), En = Mg/(Ca+Mg+Fe), Fs = Fe/(Ca+Mg+Fe). Cation amounts are used; from oxides the tool converts CaO, MgO and FeO to Ca, Mg and Fe cations first.

This gives the composition on the Wo–En–Fs ternary. Iron is treated as Fe²⁺ — do not enter total Fe as Fe²⁺ without stating the assumption. More detailed classification boundaries can follow once the composition is established.

Worked example

Ca 0.42, Mg 0.44, Fe 0.14 cations. Wo = 0.42/1.0 = 42%, En = 0.44/1.0 = 44%, Fs = 0.14/1.0 = 14% — an augite-field clinopyroxene (Wo42 En44 Fs14).

Common mistakes

  • Using oxide wt% instead of cation proportions.
  • Entering total Fe as Fe²⁺ without stating it.
  • Reading the endmembers as a full pyroxene classification.

Frequently asked questions

Does this classify the pyroxene?

It places the composition on the Wo–En–Fs quadrilateral. Detailed classification boundaries (e.g. augite vs pigeonite) are a further step from that composition.

How is iron handled?

As Fe²⁺. If you only have total iron, note that you are treating it all as ferrous — ferric iron would change the result.

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Cite this tool

Zerdly. (2026). Pyroxene Wo-En-Fs Calculator. Retrieved from https://www.zerdly.com/tools/pyroxene-wo-en-fs-calculator/

Tip: Enter any known values to calculate the remaining results.

All calculations run in your browser. Your inputs are never saved or transmitted.