White crystal granite quarries of Peña Muñana Curiosity · Cadalso de los Vidrios, Sierra Oeste, Madrid Image of Cadalso de los Vidrios, not of the place itself. The southern and eastern slopes of Peña Muñana yield a granite of great mineralogical uniformity and even tone, sold under the name blanco cristal, with an annual output of close to 8,000 cubic metres. Photo: Gema García (CC BY 3.0) What to see and do in Cadalso de los Vidrios