CIPW Norm Calculator
Convert a major-oxide analysis into the standard anhydrous CIPW norm — the calculated ideal assemblage of quartz, feldspars, feldspathoids, pyroxenes, olivine and oxides used to classify and compare igneous rocks. Everything runs in your browser and the result table is mass-balanced against your input oxides.
Major oxides (wt%)
Enter iron as FeO and Fe₂O₃ on your chosen basis — the norm uses them exactly as entered and never adjusts the Fe oxidation state for you. Blank means missing, not zero.
CIPW norm
Runs entirely in your browser. Your assay data is not uploaded or stored by Zerdly.
- Enter SiO₂ (wt%).
Assumptions & basis
- Convention: Standard anhydrous CIPW norm · MnO→FeO · Fe basis as entered · halogen-free apatite (derived)
- Iron basis: FeO and Fe2O3 used exactly as entered (no auto Fe adjustment) (user)
- Result type: Calculated normative minerals — not measured modal mineralogy (user)
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
- Enter your major oxides in wt%, giving iron as FeO and Fe₂O₃ on your chosen basis. Blank means missing, not zero.
- Read the normative minerals, each as wt% and as a percentage of the norm, plus the differentiation index and silica-saturation state.
- Normalise the analysis to ~100% first if your oxide total is well away from 100 — the tool warns when it is.
How it works
The CIPW norm converts oxide weight percentages to molecular proportions and allocates them to idealised anhydrous minerals in a fixed order: apatite, ilmenite and chromite; then orthoclase, albite and anorthite; corundum or the sodium/potassium metasilicates and acmite where alumina is short or in excess; magnetite and hematite; diopside, wollastonite and hypersthene from the remaining lime, magnesia and iron; then titanite and rutile. Manganese is added to iron(II) and the iron oxidation state is used exactly as you enter it.
The tool then balances silica. If silica is in excess the surplus becomes quartz. If it is deficient, minerals are stepped down to lower-silica equivalents in the standard order — hypersthene to olivine, titanite to perovskite, albite to nepheline, orthoclase to leucite, wollastonite and diopside to dicalcium silicate, and leucite to kaliophilite — until the balance closes. Each normative mineral's weight is summed from its constituent oxide masses, so the norm conserves oxide mass and the total matches the oxides you supplied.
The result is a calculated normative mineralogy for classification and comparison. It is not measured modal mineralogy, and the algorithm version and convention are shown so results are reproducible. The implementation is validated against stoichiometric end-members and independent reference compositions to floating-point tolerance.
Worked example
Average basalt. For a basalt with SiO₂ 49.2, Al₂O₃ 15.7, CaO 9.5, Na₂O 2.9, MgO 6.7, FeO 7.1, Fe₂O₃ 3.8, TiO₂ 1.8, K₂O 1.1, P₂O₅ 0.35 wt%, the norm is plagioclase-dominant (albite + anorthite) with diopside and hypersthene, plus magnetite, ilmenite and apatite — a silica-saturated (or marginally olivine-normative) tholeiitic assemblage. The normative total equals the oxide total.
Common mistakes
- Reading the norm as measured modal mineralogy — it is a calculated classification tool, not a point-count.
- Entering total iron as a single value: split it into FeO and Fe₂O₃, because the ratio strongly changes the norm.
- Running the norm on an analysis far from 100% without normalising first.
- Treating blanks as zeros — a missing oxide is not the same as an oxide measured at zero.
Frequently asked questions
Which CIPW convention does it use?
The standard anhydrous norm: MnO folded into FeO, iron used as entered, halogen-free apatite, and the classic desilication order. The convention string and algorithm version are shown with every result.
Why doesn't it adjust my Fe₂O₃/FeO ratio?
The iron oxidation state materially changes the norm, so the tool never alters it silently. Enter the ratio you want on your chosen basis; if you only have total iron, split it deliberately before calculating.
Does the norm total equal my oxide total?
Yes. Each normative mineral's weight is summed from its constituent oxide masses, so the norm conserves oxide mass and its total matches the oxides you entered.
Related tools
- Major Oxide Normalization Calculator
- TAS Rock Classification Calculator
- Shand Index (A/CNK & A/NK) Calculator
- Feldspar An-Ab-Or Calculator
- Elements to Oxide Calculator
- Olivine Fo-Fa Calculator
Explore more in Geology, Geotechnical & Ground Engineering.
Cite this tool
Zerdly. (2026). CIPW Norm Calculator. Retrieved from https://www.zerdly.com/tools/cipw-norm-calculator/
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.