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Related to Martite: hematite


Hematite occurring in iron-black octahedral crystals pseudomorphous after magnetite.



a mineral, the product yielded upon conversion of magnetite, Fe3O4 into hematite, Fe2O3. The crystals and crystalline grains of magnetite, upon conversion into martite, are usually replaced, without alteration of their original form, by finely aggregated hematite and exhibit the physical properties characteristic of the latter. Martite forms during the oxidation of magnetite in the weathering zone of the earth’s crust as well as deep within the earth under conditions characterized by increased oxidation potential of hydrothermal solutions surrounding the previously formed magnetite. Martite ores are high-grade iron ores.

References in periodicals archive ?
Twin peaks, Millard County, Utah, is one of the most frequently mentioned localities for hematite, variety martite, though the octahedral "crystals" found in Ouro Preto, Minas Gerais, are equally noteworthy.
There was a chance occurrence of an extraordinary number of octahedra of martite on the surface of the surrounding rock, a schistose-veined biotite gneiss.