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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 ...
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.
An ophiolite is a section of Earth's oceanic crust and the underlying upper mantle that has been uplifted and exposed, and often emplaced onto continental crustal rocks. The Greek word ὄφις, ophis (snake) is found in the name of ophiolites, because of the superficial texture of some of them. Serpentinite especially evokes a snakeskin.
Bushveld Igneous Complex geologic map and mine locations. The Bushveld Igneous Complex (BIC) is the largest layered igneous intrusion [1] [2] within the Earth's crust. [3] It has been tilted and eroded forming the outcrops around what appears to be the edge of a great geological basin: the Transvaal Basin.
It is usually found as the mineral chromite, from which ferrochrome is produced in a smelting process. Rank Country/Region Chromium ore production (tonnes)
Stillwater igneous complex around Mouat chromite mine Chromitite with bronzite phenocrysts from Stillwater Igneous Complex Sulfidic serpentintite, platinum-palladium ore from the Stillwater Mine. This is an altered pegmatitic dunite very richly infused with intercumulate Pt/Pd-rich chalcopyrite & pyrrhotite (golden metallic minerals).
Chromite and magnetite are ore minerals that form in this way. [1] Liquid immiscibility: sulfide ores containing copper, nickel, or platinum may form from this process. 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.
Under the unusual chemical conditions accompanying serpentinization, water is the oxidizing agent, and is itself reduced to hydrogen, H 2. This leads to further reactions that produce rare iron group native element minerals, such as awaruite (Ni 3 Fe) and native iron; methane and other hydrocarbon compounds; and hydrogen sulfide. [1] [6]