Iron oxide pigment
Iron oxide pigment extraction sites
Iron oxides are usually formed by precipitation from iron-enriched groundwater. Iron oxide pigments consist of ferrous or ferric oxides, and impurities such as clay and/or manganese. Natural Iron oxide pigments have been used for centuries as coloring agents. Iron oxide pigments are valued because they are nontoxic, weather resistant and they do not bleed or fade. The pigments are extracted from a range of ores including hematite, goethite, limonite, siderite, and magnetite. Hematite produces red pigments, limonite and goethite produce yellow and brown pigments, siderite produces brown and red pigments, and magnetite yields black pigments.
Open pit methods are used to mine these natural iron-oxides. The iron-oxides were formed by precipitation from iron-enriched groundwater, near the contact of the Cambrian (543 to 490 million years ago) Erwin Formation with the overlying Cambrian Shady Dolomite. Deposits, associated with gossans formed from weathering of the Cambrian rocks, are concentrated as small bodies or pockets composed of insoluble clay and iron oxide.
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