Magesium Flouride is transparent over a wide range of wavelengths, with commercial uses in optics that are also used in space telescopes, for instance.
Windows, lenses ,and prisms made of MgF2 can be used over the entire range of wavelengths from 0.12μm(vacuum ultraviolet ) to 8.0μm (infrared). High quality synthetic VUV grade MgF2 is quite expensive. Low grade MgF2 can be cheaper and used in the infrared but inferior to CaF2. MgF2 works and polishes well, but it is slightly birefringent and should be cut with the optic axis perpendicular to the plane of the window or lens.
Photonchina provides excellent MgF2 crystal components from double convex lens to right angle prism, from round wafer to wedge, which are used in testing instruments, astronomical telescope, etc.