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Iron oxide lavas are thought to be the result of immiscible separation of iron oxide magma from a parental magma of calc-alkaline or alkaline composition. [17] When erupted, the temperature of the molten iron oxide magma is about 700 to 800 °C (1,292 to 1,472 °F).
Iron(III) oxide is a product of the oxidation of iron. It can be prepared in the laboratory by electrolyzing a solution of sodium bicarbonate, an inert electrolyte, with an iron anode: 4 Fe + 3 O 2 + 2 H 2 O → 4 FeO(OH) The resulting hydrated iron(III) oxide, written here as FeO(OH), dehydrates around 200 °C. [18] [19] 2 FeO(OH) → Fe 2 O 3 ...
[6] [7] The crystallization sequence of oxide minerals such as magnetite and ulvospinel is sensitive to the oxygen fugacity of melts, [8] and separation of the oxide phases can be an important control of silica concentration in the evolving magma, and may be important in andesite genesis. [9] [10]
[31] [32] Mars has twice as much iron oxide in its outer layer as Earth does, despite their supposed similar origin. It is thought that Earth, being hotter, transported much of the iron downwards in the 1,800 kilometres (1,118 mi) deep, 3,200 °C (5,792 °F ), lava seas of the early planet, while Mars, with a lower lava temperature of 2,200 °C ...
The change of rock composition most responsible for the creation of magma is the addition of water. Water lowers the solidus temperature of rocks at a given pressure. For example, at a depth of about 100 kilometres, peridotite begins to melt near 800 °C in the presence of excess water, but near or above about 1,500 °C in the absence of water ...
Iron oxides feature as ferrous or ferric or both. They adopt octahedral or tetrahedral coordination geometry. 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 ...
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 ...
As a magma changes, parts of it may separate from the main body of magma. Two liquids that will not mix are called immiscible; oil and water are an example. In magmas, sulfides may separate and sink below the silicate-rich part of the intrusion or be injected into the rock surrounding it. These deposits are found in mafic and ultramafic rocks.