The agate/chalcedony collection continues to grow, and now contains a few fluorescent specimens. Here they all are under incandescent light.
And now illuminated under 405nm (nearly ultraviolet) light.
Fluorescence is always a nice surprise. The intense green emission is caused by inclusion of Uranyl (UO22+
) ions, which may also result in some radioactivity.
Also interesting is how the iron impurity which gives carnelian its vibrant red color is readily absorbing violet wavelengths, turning the stone black and opaque in this light.