Natural Iron Oxide Pigments
One or more ferrous or ferric oxide and many other impurities such as clay, manganese or organics are all included in the formation of the natural Iron Oxide Pigments. The most important source of Natural Iron Oxide Pigments is Hematite. Hematite is a oxide of iron having red color. The color of hematite varies from yellow to brown, such as siennas, umbers and ochers. But, these pigments can also be derived from another iron ore, i.e. Magnetite having a black color. The main characteristics of natural iron oxide pigments are: these are light fast, non bleeding, nontoxic and weather resistant.
As these pigments have various unique properties so these pigments are used for various purposes. The various uses of these pigments are in coloring concrete block, outdoor paintings and in other construction materials. The maximum mining and procession of natural iron oxide is done in USA. Pigments are in paints, wood and paper stains, linoleum, oilcloth, mortar, plaster, rubber, brick, and other pigmented materials.
The leading producer countries of these pigments are: France, India, Cyprus, Iran, Italy and Australia.
Source: United States Geological Survey Mineral Resources Program
Hematite- Fe2O3 (red)
Magnetite- Fe3O4 (brown to black)
Goethite- FeOOH.xH2O (yellow)
Lepidocrocite- FeOOH.xH2O (yellow)