Scheelite

Scheelite is a calcium with the chemical formula O (wolfram). Well-formed crystals are sought by collectors and are occasionally fashioned into gemstones when suitably free of flaws. Scheelite has been synthesized using the Czochralski process ; the material produced may be used to imitate diamond, or as a solid-state. It was also used in radium paint in the same fashion as was zinc sulphide invented a fluoroscope with a calcium tungstate-coated screen, making the images six times brighter than those with barium platinocyanide to discover X-rays in early November 1895.