Red ochre in Rajasthan

Red ochre

The dry ingredient, ochre, was mixed with some type of liquid raw material to create a rough paint. The liquid material was usually seal oil or cod liver oil.
Red ochre is pigment made from naturally tinted clay.Chemically,it is hydrated iron (III) oxide.
Ochres are non-toxic, and can be used to make an oil paint that dries quickly and covers surfaces thoroughly.

To manufacture ground ochre, ochre clay is first mined from the ground. It is then washed in order to separate sand from ochre, which can be done by hand. The remaining ochre is then dried in the sun and sometimes burned to enhance the natural color.

About the chemical structure:

Chemical name: Anhydrous iron(III)-oxide

Formula: Fe2O3

How Red Ochre is made:

Source:

Natural mineral consisting of silica and clay owing its color to iron oxide. It is found throughout the world, in many shades, in hues from yellow to brown, and faint blue. The best brown ochre comes from Cyprus. The pigment has good hiding power and excellent permanence in all media.
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Natural variety of pigment:
Colored earth is mined, ground and washed, leaving a mixture of minerals - essentially rust-stained clay. Ochre can be used raw (yellowish), or roasted for a deeper (brown-red) color from loss of water of hydration. Produces a quick-drying oil paint. Brief description of Red Ochre: Earthtones from cream to brown

Names for Red Ochre:

Pronounciation: red oak • ur

Alternative names: earth pigments

Word origin: The name "Red Ochre" comes from Greek ochros = yellow, pale yellow.

Non-English names: German :Roter Ocker Chemical name: Anhydrous iron(III)-oxide

Further reading:http://en.wikipedia.org/wiki/Red_ochre
Red Ochre and Yellow ochre, from Pigments through the ageshttp://webexhibits.org/pigments/indiv/overview/redochre.html