Earth Pigments: Composition, Types, and Use in Art

Earth pigments are natural colorants extracted from the subsoil through processes of purification, crushing, and drying. They belong to the broader category of natural pigments, which also include mineral, vegetable, and animal pigments. Earth pigments range from yellow ochres to raw and burnt umber, browns, reds, and greens. Their color is determined by dominant chemical elements: iron hydroxide yields yellow, ferric and ferrous silicates with potassium, manganese, or aluminum yield green, organic substances like lignite or peat yield brown, and iron oxides or sesquioxides yield red. Examples include Siena earth (warm yellow), yellow ochre, raw umber (greenish brown), burnt umber (dark warm brown turning pink when diluted), Venetian red (from hematite, warm and covering), Pompeian red (similar to red ochre, rich in iron oxide), and Vicenza earth (grayish, low tinting strength). The term 'earth colors' in contemporary marketing often refers to beige or taupe, not actual extracted pigments. Many commercial products use synthetic pigments, lacking the unique transparency and vibrancy of true earth pigments. The article emphasizes that earth pigments are less common in architecture than perceived and that their extraction and transformation hold great fascination.