Did you know the Romans used large gypsum crystals as sheet glass?

Gypsum is formed during the evaporation of ocean water. In abandoned Roman mines in southern Spain we can still find good samples of easily workable gypsum known as “lapis specularis,” literally, “stone mirror.” The large transparent slabs were very sought after by elites and considered sophisticated. Ancient artisans could easily slice this stone into thin slabs to be used in windows.

Source: https://www.eurolithos.org/gallery, Gallery 3 Lapiz Specularis, Italy.

Want to learn more about natural building materials? Visit EuroLithos.org. This GeoERA project aims to demonstrate how increased knowledge of the geology, characteristics and history of the use of natural stone in Europe can stimulate a more sustainable use of our stone resources:

Want to know more about ’Hispania glass’?