Earth pigments
Dig up rusty clay, grind it, and you have paint. Humans have done it for at least 100,000 years.
- Made from
- Iron-oxide clays (plus manganese for umbers)
- Oldest use
- Blombos Cave, about 100,000 years ago
- 'Burnt'
- Heated, which turns yellow iron oxide red
Earth pigments are colored clays and minerals dug from the ground, mostly tinted by iron oxides. Yellow ochre owes its color to goethite, red ochre to hematite. Add manganese and the earth turns brown: raw umber and raw sienna. Heat any of them and they redden, as the yellow iron mineral changes into the red one. That's why painters' tubes say 'burnt sienna' and 'burnt umber'.
They're the oldest paints we know. At Blombos Cave in South Africa, people mixed ochre in abalone shells about 100,000 years ago, and pieces of ochre engraved with crosshatched lines there are about 75,000 years old. Cave painters used red and yellow ochre at Altamira and Pech Merle, and a horse at Lascaux was colored with yellow ochre about 17,000 years ago.
The names are maps. Sienna was the 'earth of Siena', a Tuscan earth rich in manganese. Umber may come from Umbria in Italy or from Latin umbra, 'shadow'; scholars disagree (see umber). In the 1780s Jean-Étienne Astier of Roussillon in Provence worked out how to refine ochre on an industrial scale, and the red cliffs there were quarried for France's ochre trade.
Earth colors are cheap, stable and safe, which is why they never left the palette. Renaissance painters built flesh and shadow with them; the Impressionists mostly mixed their browns from brighter colors instead. Modern iron-oxide pigments are made synthetically, but the old names, Ochre, Sienna, Umber and terracotta, survive. Not every old brown came from the earth, though: mummy brown was ground from Egyptian mummies.
Swatches
- Yellow ochre · goethite
- Burnt sienna · heated, reddened
- Raw umber · iron plus manganese
- Red ochre · hematite (approx.)
- Terracotta · fired clay
Colors
Sources
- Henshilwood, C. S. et al. (2011). A 100,000-year-old ochre-processing workshop at Blombos Cave, South Africa. Science 334(6053): 219–222.
- Helwig, K. (2007). Iron oxide pigments. In Artists' Pigments, vol. 4. National Gallery of Art, Washington.
- Wikipedia, 'Ochre' and 'Umber'.
Hex values are screen approximations. Every page lists its sources.