Earth Pigments in Oil Paint

A practical reference for artists examining how traditional names such as ochre, sienna, umber, terra verte, and green earth relate to modern pigment composition, synthetic substitutes, and blended formulations.

Color names such as ochre, sienna, umber, terra verte, and green earth describe historical color families that were once closely tied to specific geological materials. Historically, these names referred to naturally occurring mineral pigments derived from iron-rich clays or green earth minerals such as glauconite and celadonite.

In contemporary paint manufacturing, however, these names no longer guarantee a natural mineral origin. Many oil colors bearing traditional earth names are formulated with synthetic iron oxides, synthetic green pigments, or blended mixtures designed to meet modern requirements for color consistency, availability, and cost.

This is not inherently deceptive, nor does it imply inferior performance. Synthetic iron oxides are widely used across the coatings and artists’ materials industries and are valued for their uniformity and reliability. However, the continued use of historical earth names can obscure meaningful differences in pigment origin for artists, conservators, and educators who care about material provenance, historical continuity, or mineral composition.

Purpose of this resource

This page identifies oil colors whose published Colour Index pigment codes indicate that they are synthetic or mixed, even though their product names suggest traditional natural earth pigments.

The goal is not to criticize manufacturers, but to provide artists with a clear, evidence-based framework for interpreting pigment information. In industrial supply chains, the primary drivers for pigment selection are typically color, cost, and consistency, not geological source. Artists, by contrast, often care about historical materials, mineral composition, and long-term behavior. This resource helps bridge that gap.

Pigment composition legend

Natural Earth — Pigments composed exclusively of traditional natural earth Colour Index codes such as PY43, PR102, or PG23.
Mixed — Formulations combining natural earth pigments with synthetic pigments, or using ambiguous codes where natural origin cannot be confirmed.
Synthetic — Pigments identified by Colour Index codes such as PY42, PR101, PBr6, or synthetic green pigments, regardless of traditional color name.
Indeterminate — Pigment codes (for example, PBr7) that may refer to either natural or synthetic materials, where manufacturers do not disclose the source.

Status reflects pigment composition only. It does not indicate quality, permanence, toxicity, or suitability for artistic use.

Why pigment codes matter

Colour Index pigment codes are currently the most reliable, publicly available indicator of pigment composition for artists. While they do not always specify whether a material is mined or synthesized, they often provide sufficient information to distinguish traditional natural earth pigments from modern synthetic alternatives.

Independent analytical research using techniques such as Raman spectroscopy, X-ray diffraction (XRD), and X-ray fluorescence (XRF) has demonstrated that pigments sold as earth pigments may contain synthetic components or unrelated adulterants. These findings reinforce the importance of verifying composition rather than relying on product names alone.

Consolidated table of earth-named oil colors

The table below lists oil colors discussed in this resource whose names imply natural earth pigments but whose published pigment codes indicate synthetic or mixed compositions. Links to relevant Natural Pigments and Painting Best Practices resources are provided where applicable.

Brand	Color name	Pigment code(s)	Status	Composition summary	Related links
Winsor & Newton	Yellow Ochre	PY42	Synthetic	Synthetic hydrated iron oxide	Yellow ochre oil paint
Winsor & Newton (Winton)	Yellow Ochre	PY42	Synthetic	Synthetic hydrated iron oxide	Yellow ochre oil paint
Gamblin	Yellow Ochre	PY42	Synthetic	Synthetic hydrated iron oxide	Yellow ochre oil paint
Michael Harding	Yellow Ochre	PY42	Synthetic	Synthetic hydrated iron oxide	Yellow ochre oil paint
Old Holland	Yellow Ochre	PY42	Synthetic	Synthetic hydrated iron oxide	Yellow ochre oil paint
Rembrandt (Talens)	Yellow Ochre	PY42	Synthetic	Synthetic hydrated iron oxide	Yellow ochre oil paint
Schmincke Mussini	Yellow Ochre	PY42	Synthetic	Synthetic hydrated iron oxide	Yellow ochre oil paint
Sennelier	Yellow Ochre	PY42	Synthetic	Synthetic hydrated iron oxide	Yellow ochre oil paint
Maimeri Classico	Yellow Ochre	PY42	Synthetic	Synthetic hydrated iron oxide	Yellow ochre oil paint
Winsor & Newton	Raw Sienna	PY42	Synthetic	Synthetic hydrated iron oxide	Yellow ochre oil paint
Winsor & Newton	Burnt Sienna	PR101	Synthetic	Synthetic anhydrous iron oxide	Burnt sienna oil paint
Gamblin	Raw Sienna	PY42	Synthetic	Synthetic hydrated iron oxide	Raw sienna oil paint
Gamblin	Burnt Sienna	PR101	Synthetic	Synthetic anhydrous iron oxide	Burnt sienna oil paint
Michael Harding	Raw Sienna	PY42 or PBr7	Indeterminate	Iron oxide; natural or synthetic, not clearly declared	Raw sienna oil paint
Michael Harding	Burnt Sienna	PR101	Synthetic	Synthetic anhydrous iron oxide	Burnt sienna oil paint
Winsor & Newton	Raw Umber	PBr7	Indeterminate	Iron oxide brown; natural or synthetic	Umber oil paint
Winsor & Newton	Burnt Umber	PBr7	Indeterminate	Iron oxide brown; natural or synthetic	Umber oil paint
Gamblin	Raw Umber	PBr7	Indeterminate	Iron oxide brown; natural or synthetic	Umber oil paint
Gamblin	Burnt Umber	PBr7	Indeterminate	Iron oxide brown; natural or synthetic	Umber oil paint
Michael Harding	Raw Umber	PBr6	Synthetic	Synthetic brown iron oxide	Umber oil paint
Michael Harding	Burnt Umber	PBr6	Synthetic	Synthetic brown iron oxide	Umber oil paint
Winsor & Newton (Winton)	Terre Verte	PG23 + PG7	Mixed	Natural green earth plus phthalocyanine green	Green earth oil paint
Maimeri Classico	Green Earth	PG23 + PG7	Mixed	Natural green earth plus phthalocyanine green	Green earth oil paint
M. Graham	Green Earth	PBr7 + PG7	Mixed	Iron oxide plus phthalocyanine green	Green earth oil paint
Sennelier	Green Earth	PG7 + PG17 + PY42	Synthetic	Synthetic blend of green and iron oxide pigments	Green earth oil paint
Rembrandt (Talens)	Green Earth	PG7	Synthetic	Phthalocyanine green	Green earth oil paint

What to do as an artist or educator

Check the Colour Index pigment code on every tube or product listing rather than relying on the color name.
Interpret the code in context. A traditional name does not guarantee a traditional material.
If geological origin matters to your work, ask suppliers for source information, or seek mineral analysis when possible.
Keep studio records of pigments used, especially for long-term or conservation-sensitive projects.

Final note

The continued use of historical earth pigment names reflects long-standing conventions within the artists’ materials industry. Understanding how those conventions intersect with modern pigment manufacturing allows artists to make informed, intentional material choices—whether their priority is color matching, historical practice, or mineral authenticity.