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Maghemite (Fe 2 O 3, γ-Fe 2 O 3) is a member of the family of iron oxides.It has the same formula as hematite, but the same spinel ferrite structure as magnetite (Fe 3 O 4) and is also ferrimagnetic.
Iron(II,III) oxide, or black iron oxide, is the chemical compound with formula Fe 3 O 4.It occurs in nature as the mineral magnetite.It is one of a number of iron oxides, the others being iron(II) oxide (FeO), which is rare, and iron(III) oxide (Fe 2 O 3) which also occurs naturally as the mineral hematite.
Only a few oxides are significant at the earth's surface, particularly wüstite, magnetite, and hematite. Oxides of Fe II. FeO: iron(II) oxide, wüstite; Mixed oxides of Fe II and Fe III. Fe 3 O 4: Iron(II,III) oxide, magnetite; Fe 4 O 5 [2] Fe 5 O 6 [3] Fe 5 O 7 [4] Fe 25 O 32 [4] Fe 13 O 19 [5] Oxides of Fe III. Fe 2 O 3: iron(III) oxide. α ...
The magnetic structure of α-hematite was the subject of considerable discussion and debate during the 1950s, as it appeared to be ferromagnetic with a Curie temperature of approximately 1,000 K (730 °C), but with an extremely small magnetic moment (0.002 Bohr magnetons). Adding to the surprise was a transition with a decrease in temperature ...
Magnetite has been important in understanding the conditions under which rocks form. Magnetite reacts with oxygen to produce hematite, and the mineral pair forms a buffer that can control how oxidizing its environment is (the oxygen fugacity). This buffer is known as the hematite-magnetite or HM buffer.
Wüstite, in geochemistry, defines a redox buffer of oxidation within rocks at which point the rock is so reduced that Fe 3+, and thus hematite, is absent. As the redox state of a rock is further reduced, magnetite is converted to wüstite. This occurs by conversion of the Fe 3+ ions in magnetite to Fe 2+ ions. An example reaction is presented ...
Black sand is sand that is black in color. One type of black sand is a heavy, glossy, partly magnetic mixture of usually fine sands containing minerals such as magnetite, found as part of a placer deposit. Another type of black sand, found on beaches near a volcano, consists of tiny fragments of basalt.
Hematite - titanomagnitite. Titanomagnetite is a mineral containing oxides of titanium and iron, with the formula Fe 2+ (Fe 3+,Ti) 2 O 4. It is also known as titaniferous magnetite, mogensenite, Ti-magnetite, or titanian magnetite. [1] It is part of the spinel group of minerals.