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Native iron from basalt quarry at Bühl, Weimar, district of Kassel, Germany (size: 6.6 × 5.9 × 1.8 cm) In addition to the Disko Island deposit native iron has been reported from Fortune Bay, Mellemfjord, Asuk, and other locations along Greenland's west coast. Other locations include: [1] Ben Breck, Scotland in granite with magnetite [8]
The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic series. A magma series is a series of compositions that describes the evolution of a mafic magma, which is high in magnesium and iron and produces basalt or gabbro, as it fractionally crystallizes to become a felsic magma, which is low in ...
When the iron content of the melt is sufficiently high, magnetite or ilmenite crystallise and, due to their high density, form cumulate rocks. Chromite is generally formed during pyroxene fractionation at low pressures, where chromium is rejected from the pyroxene crystals.
They are distinguished by comparing total alkali with iron and magnesium content. [23] These three magma series occur in a range of plate tectonic settings. Tholeiitic magma series rocks are found, for example, at mid-ocean ridges, back-arc basins, oceanic islands formed by hotspots, island arcs and continental large igneous provinces. [24]
Tholeiitic rock types tend to be more enriched in iron and less enriched in aluminium than calc-alkaline rock types. They are thought to form in a less oxidized environment than calc-alkaline rocks. Tholeiitic basalt is formed at mid-ocean ridges and makes up much of the oceanic crust. Almost all the basalt found on the Moon is tholeiitic basalt.
Ulvöspinel was first described by Fredrik Mogensen (1904–1978) [5] from a dolerite layered intrusion in the Ulvö Islands, Ångermanland, Sweden in 1943. The locality is an iron, titanium and vanadium mining area that has been active since the 17th century. [6] It is common in titaniferous magnetite iron ore deposits.
Ceylonite, named for the island of Ceylon, is a ferroan spinel with Mg:Fe from 3:1 and 1:1, and little or no ferric iron. Pleonaste is named from the Greek for 'abundant,' for its many crystal forms, and is distinguished chemically by low Mg:Fe ratios of approximately 1:3. It is sometimes used as a gemstone. [2]
The crystals are captured, stored, and sputter-coated with platinum at cryo-temperatures for imaging. The crystallization process appears to violate the second principle of thermodynamics. Whereas most processes that yield more orderly results are achieved by applying heat, crystals usually form at lower temperatures – especially by ...