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Ochre (/ ˈ oʊ k ər / OH-kər; from Ancient Greek ὤχρα (ṓkhra), from ὠχρός (ōkhrós) 'pale'), iron ochre, or ocher in American English, is a natural clay earth pigment, a mixture of ferric oxide and varying amounts of clay and sand. [2]
[1] [2] Other earth pigments include the green earth pigments or terres vertes, blue earth pigments such as vivianite-based "blue ochre", white earth pigments such as chalk, and black earth pigments such as charcoal. [3] [4] Earth pigments are known for their fast drying time in oil painting, relative inexpensiveness, and lightfastness. Cave ...
Ochre is a clay that is colored by varying amounts of hematite, varying between 20% and 70%. [9] Red ochre contains unhydrated hematite, whereas yellow ochre contains hydrated hematite (Fe 2 O 3 · H 2 O). The principal use of ochre is for tinting with a permanent color. [9]
Red ochre takes its reddish colour from the mineral hematite, which is an anhydrous iron oxide, and the main ingredient of rust. It was one of the earliest pigments used by man. Hand prints made by using red ochre have been found in the Pech Merle cave in Southern France. They date to between 16,000 and 25,000 BC.
Attic ochre or attic yellow ocher (Latin: Sil atticum) — the historically known variety of ochre, which had a bright lemon yellow color, was considered the best and most expensive type of ochre in Ancient Greece and Rome. Attic ochre was used mainly for high-quality finishing work or decoration of household items.
Goethite is an important component of ochre pigments, [21] and has been heat-treated for use as a red pigment since Paleolithic times. [22] Iron-rich lateritic soils that have developed over serpentinite rocks in tropical climates are mined for their iron content, as well as other metals. [23]
The anhydrous pigment has a dark purple-red or maroon color, hydrates' colors vary from dull yellow (yellow ochre) to warm red. [1]The iron oxide red is extremely stable: it is not affected by light and most chemicals (soluble in hot concentrated acids); heat only affects the hydrated variants (the water is removed, and the color darkens).
The Ochre Coloured Pottery culture (OCP) is a Bronze Age culture of the Indo-Gangetic Plain "generally dated 2000–1500 BCE," [1] [2] extending from eastern Punjab to northeastern Rajasthan and western Uttar Pradesh. [3] [4] Artefacts of this culture show similarities with both the Late Harappan culture and the Vedic culture.