Green light from the rocks of the Aladzha Monastery

The remains of the Aladzha Monastery on the Black Sea coast are located just above the port city of Varna, Bulgaria. In the very distant past, this monastery was carved out of a steep rock wall consisting of limestone. The monastery is formed by small caves situated at different levels in the rock wall.

In the photos of some pieces of limestone you can recognize the powdery structure of this soft limestone. 

However, let’s still have a look under the fluorescence microscope then; blue light excitation and FITC filter.  As can you see, green light, this white limestone shows auto fluorescence.