The red fluorescence of this calcite is caused by manganese replacing calcium. Mn2+ in calcite requires UV of about 320 nm to fluoresce. This excitation energy is supplied by lead that replaces calcium (a few ppm). It is therefore the fluorescence of Pb2+ that supplies the right UV wavelengths for this fluorescence.
Measured with: Ocean Optics Flame spectrometer, backscattering /reflection probe and a LED light source of 255 nm.
