Ochre

Ochre refers to a group of natural earth pigments made from clay, colored by ferric oxide and mixed with varying amounts of clay and sand. These pigments range in shade from yellow to deep orange or brown. The word also describes the colors these pigments produce, particularly a light brownish-yellow. The term comes from the Ancient Greek *ṓkhra*, derived from *ōkhrós*, meaning "pale."

In American English, it is sometimes spelled "ocher." The ochre family includes yellow ochre, red ochre, purple ochre, sienna, and umber. The main ingredient in all ochres is iron(III) oxide-hydroxide, known as limonite, which gives them their yellow color. Other minerals may also be present. Clays colored by iron oxide from tin and copper extraction are sometimes also called ochre.

The range of ochre colors includes: - **Yellow ochre** (also called gold ochre): hydrated iron(III) oxyhydroxide (limonite). - **Red ochre**: takes its reddish tint from hematite, an iron oxide that appears reddish brown when hydrated. In some English dialects, it is called ruddle. - **Purple ochre**: chemically identical to red ochre but with a different hue due to larger particle size affecting light diffraction. - **Brown ochre**: partly hydrated iron oxide (goethite), also found in the mineral lepidocrocite. - **Sienna**: contains limonite and a small amount of manganese oxide (less than 5%), making it darker. - **Umber**: contains a larger proportion of manganese (5–20%), giving it a dark brown color.

Historically, ochre has been used for tens of thousands of years. In Africa, evidence of red ochre processing dates to around 300,000 years ago, with its peak use coinciding with the emergence of *Homo sapiens*. In Australia, ochre use appears from about 50,000 years ago, and in Asia from around 40,000 years ago. Prehistoric people selected ochre based on qualities like color, texture, and hardness. In parts of Southern Africa, deep red ochres were transported over long distances despite local deposits, suggesting each pigment held unique cultural or ritual significance. This movement indicates early long-distance exchange networks.

At Le Moustier in France, stone tools from the Mousterian period were found with handles made from a mixture of 55% ground goethite ochre and 45% cooked bitumen. This compound adhesive, dating between 60,000 and 35,000 years ago, is the earliest evidence of such technology in Europe and is associated with Neanderthals. Engraved ochre pieces from Blombos Cave in South Africa date to around 75,000 years ago. In Australia, the burial of "Mungo Man" included a sprinkling of red ochre about 40,000 years ago. The "Red Lady of Paviland" in Wales, a Paleolithic burial coated in red ochre, dates to around 33,000 years ago. Animal paintings using red and yellow ochre appear at Pech Merle in France (about 25,000 years old), Altamira in Spain (c. 16,500–15,000 BC), and Lascaux in France, which has a horse colored with yellow ochre estimated at 17,300 years old. Neolithic burials may have used red ochre symbolically, representing a return to the earth or ritual rebirth, with the color possibly symbolizing blood.

Ochre use was sometimes intensive: cave floors have been found impregnated with purplish red to a depth of eight inches, raising unresolved questions about the scale of use. It is thought that Aurignacian people regularly painted their bodies red, dyed animal skins, coated weapons, and sprinkled dwelling floors with ochre. The Gothic historian Jordanes wrote that ancient Caledonians painted themselves "Iron Red," whether for adornment or another reason. Ochre also has non-paint uses, as tribal peoples today still employ it for various purposes.