Lapis Specularis: the stone glass

The Crystal Trail is a hiking trail that runs from Monte Mauro and connects Roman lapis specularis mines. Lapis specularis was a semitransparent stone made from selenite, a gypsum mineral. The Romans used it to create windows, stained glass and other objects. The Romans knew how to make glass very well, but they could not make plate glass. Roman glass, in fact, was produced by blowing it into clay forms. This process made it possible to produce objects of complex shape, but not flat plates.

Lapis specularis was an alternative solution to glass. It was a semi-transparent stone that could be cut and polished to create thin slabs. Lapis specularis was used to create windows, stained glass windows and other objects.

The Crystal Trail is an excellent opportunity to learn about the history of lapis specularis. Along the trail you can visit ancient Roman mines and see the remains of structures used for mining and stone processing.