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Red ochre, Fe 2 O 3 ·nH 2 O, takes its reddish colour from the mineral hematite, which is an iron oxide, reddish brown when hydrated. [7] Purple ochre is a rare variant identical to red ochre chemically but of a different hue caused by different light diffraction properties associated with a greater average particle size.
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.
Cerium sulfide red (PR265). Iron oxide pigments. Sanguine, Caput mortuum, Indian red, Venetian red, oxide red (PR102). Red ochre (PR102): anhydrous Fe 2 O 3. Burnt sienna (PBr7): a pigment produced by heating raw sienna. Lead pigments. Minium (pigment): also known as red lead, lead tetroxide, Pb 3 O 4. Mercury pigments. Vermilion or cinnabar ...
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).
In 2022 a team of South African and French scientists published a study of otjize's physical properties, concluding that "such a red ochre exhibits an exceptional UV filtration and a significant IR reflectivity substantiating its effectiveness as an effective UV-blocking and solar heat IR reflector in support of the low skin cancer rate within the Namibian Himba community".
Egyptian women used red ochre as a cosmetic to redden cheeks and lips [56] and also used henna to color their hair and paint their nails. [57] The ancient Romans wore togas with red stripes on holidays, and the bride at a wedding wore a red shawl, called a flammeum. [4]: 46 Red was used to color
The U.S. Food and Drug Administration is moving to ban the use of Red No. 3 dye in food products. The agency said Wednesday it is amending its color additive regulations to no longer allow the use ...
The metals and common colours of heraldry. One system of hatching is shown at right. Tinctures are the colours, metals, and furs used in heraldry.Nine tinctures are in common use: two metals, or (gold or yellow) and argent (silver or white); the colours gules (red), azure (blue), vert (green), sable (black), and purpure (purple); and the furs ermine, which represents the winter fur of a stoat ...