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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 chemistry, a tungstate is a compound that contains an oxyanion of tungsten or is a mixed oxide containing tungsten. The simplest tungstate ion is WO 2− 4 , "orthotungstate". [ 1 ] Many other tungstates belong to a large group of polyatomic ions that are termed polyoxometalates , ("POMs"), and specifically termed isopolyoxometalates as they ...
Tungsten is a mostly non-reactive element: it does not react with water, is immune to attack by most acids and bases, and does not react with oxygen or air at room temperature. At elevated temperatures (i.e., when red-hot) it reacts with oxygen to form the trioxide compound tungsten(VI), WO 3 .
Powellite (calcium molybdate) and scheelite (calcium tungstate) fluoresce intrinsically in yellow and blue, respectively. When present together in solid solution , energy is transferred from the higher-energy tungsten to the lower-energy molybdenum , such that fairly low levels of molybdenum are sufficient to cause a yellow emission for ...
He invented a fluorescent lamp in 1896 that used a coating of calcium tungstate as the fluorescing substance, excited by X-rays. Although it received a patent in 1907, [6] it was not put into production. As with a few other attempts to use Geissler tubes for illumination, it had a short operating life, and given the success of the incandescent ...
The water districts said California’s water operations are “incredibly complex” and that the movement of water supplies “requires an extensive understanding of the plumbing, safety ...
4 or calcium tungstate: exhibits long decay time 9 μs and short wavelength emission with maximum at 420 nm matching sensitivity curve of bi‑alkali PMT. [7] The light yield and energy resolution of the scintillator (6.6% for 137 Cs) is comparable with that of CdWO 4. [53]
The average salary for a water resource specialist is $157,740 per year. And the Bureau of Labor Statistics (BLS) estimates 8% job growth, which is much higher than average. This means that you ...