Category:Ochre

Ochre is a family of earth pigments, which includes yellow ochre, red ochre, purple ochre, sienna, and umber. The major ingredient of all the ochres is iron oxide-hydroxide, known as limonite, which gives them a yellow colour. Yellow ochre, is a hydrated iron hydroxide (limonite) also called gold ochre. Red ochre, takes its reddish colour from the mineral hematite, which is an anhydrous iron oxide. Purple ochre is identical to red ochre chemically but of a different hue caused by different light diffraction properties associated with a greater average particle size. Brown ochre, (goethite), is a partly hydrated iron oxide.

Sienna contains both limonite and a small amount of manganese oxide, which makes it darker than ochre. Umber pigments contain a larger proportion of manganese, which makes them a dark brown.

Yvert model for Ocre. German: Gelborange