Simple campfire chemistry hints how ancient humans produced pigments

Chemists in the US have shown how ancient humans could have accidentally discovered a simple and easy way to make red ochre – one of the earliest pigments used by humans – by roasting lumps of a common brown mineral in campfires. The work offers fresh insight into red ochre’s prominence and ubiquity across human cultures.

Archaeological evidence points to humans using ochre pigments over 300,000 years ago, with uses ranging from body paint to art and ritual. Ochre is a mixture of sand, clay and iron oxide minerals, which give it hues ranging from yellow to red. Goethite produces brown ochre while haematite is responsible for red ochre. Both occur naturally, mainly in rocks and soils, so developing ways to manufacture haematite was not essential for humans to produce red ochre.