The “glowing mystery” of the Bologna Stone was a subject of intrest in io9.com blog lately. To give more insight on the scientific details of the persistent luminescence in Bologna Stone, have a look at our paper published in 2012.

Lastusaari, M., Laamanen, T., Malkamäki, M., Eskola, K.O., Kotlov, A., Carlson, S., Welter, E., Brito, H.F., Bettinelli, M., Jungner, H., and Hölsä, J., The Bologna Stone: history’s first persistent luminescence material, Eur. J. Mineral. 24 (2012) 885-890.
Read online: http://dx.doi.org/10.1127/0935-1221/2012/0024-2224

io9 blog: http://io9.com/the-bologna-stone-was-a-glowing-mystery-for-400-years-1724589932