In daylight, this specimen is something most collectors would not even bother looking at; but since I knew calcite from this locale, especially "optical calcite", can be pretty gorgeous in midwave UV (see: https://www.naturesrainbows.com/post/optical-calcite-gatineau-area-quebec-canada), I decided to take a look at this non-gemmy, white calcite cleavage under midwave, and I didn't regret taking time to do so.
This specimen is at its best under MW & LW combined; most colors are the reaction of this specimen to MW; however, small zones of yellow fluorescence are brighter under LW. The areas that fluoresce bright red under midwave shift to a yellow-orange color under shortwave. The SW response is weaker than MW. Nice specimen for a midwave UV display.
Size: 6,7 cm X 6 cm X 1,2 cm
In the slideshow below, the specimen is shown, respectively under MW + LW, MW, SW then in visible light.