The lapis specularis trade Historical milestone · Saelices, La Mancha Conquense, Cuenca Image of Saelices, not of the place itself. The selenite gypsum extracted in the mines of this comarca, the lapis specularis that Pliny cited as the best in the empire, served as glass for Roman windows. Its trade explains the monumental wealth that Segóbriga attained in the first century. siglo I Photo: Malopez 21 (CC BY-SA 4.0) What to see and do in Saelices