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The tholeiitic magma series (/ ˌ θ oʊ l eɪ ˈ ɪ t ɪ k /) is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic magma into a more evolved, silica rich end member.
Under reflected light, magnetite shows up as metallic and a silver or black color. Hematite will be a more reddish-yellow color. Pyrite is seen as opaque, a yellow-gold color, and metallic. [12] Chamosite is an olive-green color in thin section that readily oxidizes to limonite. When it is partially or fully oxidized to limonite, the green ...
The streak of limonite on an unglazed porcelain plate is always yellowish brown, a character which distinguishes it from hematite with a red streak, or from magnetite with a black streak. The hardness is quite variable, ranging from 1 to 5. In thin section it appears as red, yellow, or brown and has a high index of refraction, 2.0–2.4.
Rutile grains as accessory post-kinematic mineral in highly deformed mica-rich zone. Photomicrograph from thin section in cross and plane polarised light. Magnetite is the most common accessory mineral in the ore rocks, and constitute usually less than 1 vol% of the ore. It is mostly found in the glimmerites. [53]
Vacancies lower the crystal symmetry. Therefore, monoclinic forms of pyrrhotite are in general more defect-rich than the more symmetrical hexagonal forms, and thus are more magnetic. [11] Monoclinic pyrrhotite undergoes a magnetic transition known as the Besnus transition at 30 K that leads to a loss of magnetic remanence. [12]
Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe 2+ Fe 3+ 2 O 4. It is one of the oxides of iron, and is ferrimagnetic; [6] ...
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]
Hausmannite is a complex oxide, or a mixed oxide, of manganese containing both di-and tri-valent manganese. Its chemical formula can be represented as Mn II Mn III 2 O 4, or more simply noted as MnO·Mn 2 O 3, or Mn 3 O 4, as commonly done for magnetite (Fe 3 O 4), the corresponding iron oxide.