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Michel-Lévy interference colour chart issued by Zeiss Microscopy. In optical mineralogy, an interference colour chart, also known as the Michel-Levy chart, is a tool first developed by Auguste Michel-Lévy to identify minerals in thin section using a petrographic microscope.
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]
AFM diagram showing the relative proportions of the oxides of alkalis (A), iron (F), and magnesium (M), with arrows showing the compositional change path of the magmas in the tholeiitic and the calc-alkaline magma series (BT=tholeiitic basalt, FB=ferro-basalt, ABT=tholeiitic basaltic andesite, AT=tholeiitic andesite, D=dacite, R=rhyolite, B=basalt, AB=basaltic andesite, A=andesite; dashed line ...
A and B can also be the same metal with different valences, as is the case with magnetite, Fe 3 O 4 (as Fe 2+ Fe 3+ 2 O 2− 4), which is the most abundant member of the spinel group. [3] Spinels are grouped in series by the B cation. The group is named for spinel (MgAl 2 O 4), which was once known as "spinel ruby". [4] (Today the term ruby is ...
A sample of granodiorite from Massif Central, France QAPF diagram for classification of plutonic rocks Mineral assemblage of igneous rocks Photomicrograph of thin section of granodiorite from Slovakia (in crossed polarised light)
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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.
Maghemite forms by weathering or low-temperature oxidation of spinels containing iron(II) such as magnetite or titanomagnetite. Maghemite can also form through dehydration and transformation of certain iron oxyhydroxide minerals, such as lepidocrocite and ferrihydrite.