Yttrofluorite is a variety of fluorite in which the rare earth element yttrium substitutes for some of the calcium in the fluorite structure. In this specimen, two prominent veins of light grey/white yttrofluorite are encased in a mass of pegmatite with blades of grey muscovite, pink feldspar (var. unkn) and milky quartz. This piece was collected in 2000 at the Joseph Mine, Rio Arriba County, New Mexico, and measures 75 x 51 x 50 mm.
As shown in the following photographs, the yttrofluorite in this specimen shows a multi-colored, multi-wavelength fluorescent response under UV.
In the photograph above, the yttrofluorite fluoresces bright pale yellow under short wave UV (254 nm). Dim red fluorescent feldspar can also be seen.
Under mid wave UV (302 nm) the yttrofluorite shows a pale blue/white fluorescent response.
Under long wave UV (365 nm) the yttrofluorite shows a pale blue fluorescent response.
Same specimen shown under visible light.