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In addition to the way the different compositions influenced texture, the way Egyptian blue was processed also had an effect on its texture, in terms of coarseness and fineness. Following a number of experiments, Tite et al. concluded that for fine-textured Egyptian blue, two stages were necessary to obtain uniformly interspersed crystals ...
Group I kimberlites exhibit a distinctive inequigranular texture caused by macrocrystic (0.5–10 mm or 0.020–0.394 in) to megacrystic (10–200 mm or 0.39–7.87 in) phenocrysts of olivine, pyrope, chromian diopside, magnesian ilmenite, and phlogopite, in a fine- to medium-grained groundmass.
A modern parallel to ancient miners seeking luminous gems at nighttime is mineworkers using portable shortwave ultraviolet lamps to locate ores that respond with color-specific fluorescence. For instance, under short-wave UV light, scheelite , a tungsten ore, fluoresces a bright sky-blue, and willemite , a minor ore of zinc , fluoresces green ...
Scheelite is a calcium tungstate mineral with the chemical formula Ca W O 4.It is an important ore of tungsten (wolfram). Scheelite is originally named after Swedish chemist Carl Wilhelm Scheele (1742–1786).
Willemite is a zinc silicate mineral (Zn 2 Si O 4) and a minor ore of zinc.It is highly fluorescent (green) under shortwave ultraviolet light. It occurs in a variety of colors in daylight, in fibrous masses and apple-green gemmy masses.
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This porphyritic texture is indicative of multi-stage cooling of magma. For example, porphyritic andesite will have large phenocrysts of plagioclase in a fine-grained matrix. Also in South Africa , diamonds are often mined from a matrix of weathered clay -like rock ( kimberlite ) called "yellow ground".
Ilmenite is a titanium-iron oxide mineral with the idealized formula FeTiO 3.It is a weakly magnetic black or steel-gray solid. Ilmenite is the most important ore of titanium [5] and the main source of titanium dioxide, which is used in paints, printing inks, [6] fabrics, plastics, paper, sunscreen, food and cosmetics.