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White veins in dark rock at Imperia, Italy. In geology, a vein is a distinct sheetlike body of crystallized minerals within a rock. Veins form when mineral constituents carried by an aqueous solution within the rock mass are deposited through precipitation. The hydraulic flow involved is usually due to hydrothermal circulation. [1]
Quartz reef mining is a type of gold mining in "reefs" (veins [1]) of quartz. Quartz is one of the most common minerals in the Earth's crust, and most quartz veins do not carry gold, but those that have gold are avidly hunted by prospectors. In the shallow, oxidized zones of quartz reef deposits, the gold occurs in its metallic state, and is ...
Boudinage is a geological term for structures formed by extension, where a rigid tabular body such as hornfels, is stretched and deformed amidst less competent surroundings. [1] The competent bed begins to break up, forming sausage-shaped boudins. Boudinage is common and can occur at any scale, from microscopic to lithospheric, and can be found ...
The epithermal vein deposit (EVP) is a type of mineral deposit that forms in the shallow subsurface, typically at depths of less than 1,500 meters below the Earth's surface. [1] These deposits are formed by hot, mineral-rich fluids that circulate through fractures and cracks in rocks. As the fluids cool, they deposit minerals, such as gold ...
Quartz. Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO 4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO 2. Quartz is, therefore, classified structurally as a framework silicate mineral ...
Wolframite is an iron, manganese, and tungstate mineral with a chemical formula of (Fe,Mn)WO4 that is the intermediate mineral between ferberite (Fe2+ rich) and hübnerite (Mn2+ rich). [4] Along with scheelite, the wolframite series are the most important tungsten ore minerals. Wolframite is found in quartz veins and pegmatites associated with ...
Kyanite is a typically blue aluminosilicate mineral, found in aluminium -rich metamorphic pegmatites and sedimentary rock. It is the high pressure polymorph of andalusite and sillimanite, and the presence of kyanite in metamorphic rocks generally indicates metamorphism deep in the Earth's crust. Kyanite is also known as disthene or cyanite.
Magnesite occurs as veins in and an alteration product of ultramafic rocks, serpentinite and other magnesium rich rock types in both contact and regional metamorphic terrains. These magnesites are often cryptocrystalline and contain silica in the form of opal or chert.