Which metal is obtained from minerals haematite and magnetite?
Magnetite for magnetohydrodynamics and other scientific fields. The relationships between magnetite and other iron-rich oxide minerals such as ilmenite, hematite, and ulvospinel have been much studied; the reactions between these minerals and oxygen influence how and when magnetite preserves a record of the Earth's magnetic field. At low temperatures, magnetite undergoes a crystal structure phase transition from a monoclinic structure to a cubic structure known as the Verwey transition. Optical studies show that this metal to insulator transition is sharp and occurs around 120 K. The Verwey transition is dependent on grain size, domain state, pressure, and the iron-oxygen stoichiometry. An
Magnetite member of the spinel group, magnetite can form solid solutions with similarly structured minerals, including ulvospinel (FeTiO), hercynite (FeAlO) and chromite (FeCrO). Titanomagnetite, also known as titaniferous magnetite, is a solid solution between magnetite and ulvospinel that crystallizes in many mafic igneous rocks. Titanomagnetite may undergo oxyexsolution during cooling, resulting in ingrowths of magnetite and ilmenite. Natural and synthetic magnetite occurs most commonly as octahedral crystals bounded by {111} planes and as rhombic-dodecahedra. Twinning occurs on the {111} plane. Hydrothermal synthesis usually produce single octahedral crystals which can be as large as 10mm across. In the presence of mineralizers such