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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). Well-formed crystals are sought by collectors and are occasionally fashioned into gemstones when suitably free of flaws.
In metallurgy, the Scheil-Gulliver equation (or Scheil equation) describes solute redistribution during solidification of an alloy. Solidification of a binary Cu Zn alloy, with composition of 30% of Zinc in weight, using open version of Computherm Pandat. Red line is following lever rule, while Scheil model applies to the blue one
Wolframite is an iron, manganese, and tungstate mineral with a chemical formula of (Fe,Mn)WO 4 that is the intermediate mineral between ferberite (Fe 2+ rich) and hübnerite (Mn 2+ rich). [4] Along with scheelite, the wolframite series are the most important tungsten ore minerals.
The name tungsten (which means ' heavy stone ' in Swedish and was the old Swedish name for the mineral scheelite and other minerals of similar density) is used in English, French, and many other languages as the name of the element, but wolfram (or volfram) is used in most European (especially Germanic and Slavic) languages and is derived from ...
The crystal structure of APR resembles that of scheelite, with atomic cation is replaced by ammonium. The pertechnetate (NH 4 TcO 4 ), periodate (NH 4 IO 4 ), tetrachlorothallate (NH 4 TlCl 4 ), and tetrachloroindate (NH 4 InCl 4 ) follow this motif. [ 4 ]
Huttonite is a thorium nesosilicate mineral with the chemical formula Th Si O 4 and which crystallizes in the monoclinic system. It is dimorphous with tetragonal thorite, and isostructual with monazite. An uncommon mineral, huttonite forms transparent or translucent cream–colored crystals.
An example of the tetragonal crystals, wulfenite Two different views (top down and from the side) of the unit cell of tP30-CrFe (σ-phase Frank–Kasper structure) that show its different side lengths, making this structure a member of the tetragonal crystal system.
Scheelite is treated similarly using sodium carbonate. Sodium tungstate can also be produced by treating tungsten carbide with a mixture of sodium nitrate and sodium hydroxide in a fusion process which overcomes the high exothermicity of the reaction involved. Several polymorphs of sodium tungstate are known, three at only one atmosphere ...