Making Natural Earth Pigments from Soil and Rocks — Collecting and Processing

Create artist-quality pigments from naturally coloured soils and rocks using levigation (water-based particle separation), grinding, and optional calcination. Earth pigments — the ochres, siennas, and umbers — are among the oldest colouring materials in human history, used in the Lascaux cave paintings (17,000 years ago) and continuously through to modern times. Their colour comes from iron oxide minerals: goethite (FeOOH) produces yellows and browns, hematite (Fe2O3) produces reds, and manganese dioxide (MnO2) adds the dark tones in umbers. This blueprint covers collecting raw material, purifying it into fine pigment, and calcining (heat-treating) to transform yellow ochre into red ochre.