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Chromite can also be presented in a thin section. The grains seen in thin sections are disseminated with crystals that are euhedral to subhedral. [12] Chromite contains Mg, ferrous iron [Fe(II)], Al and trace amounts of Ti. [5] Chromite can change into different minerals based on the amounts of each element in the mineral.
Dark layers of chromite-rich cumulate rock alternating with light layers of plagioclase-rich rock in the Bushveld Igneous Complex, South Africa Oxide mineral cumulates form in layered intrusions when fractional crystallisation has progressed enough to allow the crystallisation of oxide minerals which are invariably a form of spinel .
Thin sections are prepared in order to investigate the optical properties of the minerals in the rock. This work is a part of petrology and helps to reveal the origin and evolution of the parent rock. A photograph of a rock in thin section is often referred to as a photomicrograph.
Altered samples of the Blue Ridge Ophiolite are green, with white and black crystals that are visible. In thin section some samples have no olivine such as the sample form Todd, North Carolina. Altered minerals that can be seen in thin section are chlorite and chromite. [3] Sample of Talc-Actinolite Schist taken from Todd, North Carolina ...
The following tests are some examples of those that are used on hand specimens, or on field samples, or on thin sections with the aid of a polarizing microscope. Color; Color of the mineral. Color alone is not diagnostic. For example quartz can be almost any color, depending on minor impurities and microstructure. Streak
The mineral chromite is an iron chromium oxide with empirical formula FeCr 2 O 4. Structurally, it belongs to the spinel group. Magnesium can substitute for iron in variable amounts as it forms a solid solution with magnesiochromite (MgCr 2 O 4);. [1] Zincochromite is another example.
Fuchsite, also known as chrome mica, is a chromium (Cr)-rich variety of the mineral muscovite, belonging to the mica group of phyllosilicate minerals, with the chemical formula K(Al,Cr) 2 (AlSi 3 O 10)(OH) 2.
At higher temperatures, it will be altered to iron-rich chromite (ferrit-chromite). [28] During serpentinization, the rock is enriched in chlorine , boron , fluorine , and sulfur. Sulfur will be reduced to hydrogen sulfide and sulfide minerals, though significant quantities are incorporated into serpentine minerals, and some may later be ...