Blue, one of the rarest colors for Quartz, is only caused by inclusions of other inherently blue minerals rather than coloration imparted by minor impurities. (How iron impurities are responsible for the purple in amethyst) La Juanona Quarry is one of the most classic blue quartz localities in Europe, recognizable by the small Cumberland habit quartz crystals it produces. These specimens, with individual crystal to 2.8 cm, are among the finest Blue Quartz ever found in Spain. They were collected by my good friend Jose Luis Valdes who after 20+ years of collecting at La Juanona quarry had considered these to be "la cabeza" (the head) of his collection. On my visits to Spain I purchased specimens from the body of his collection until this last summer when I went home with the rest, including "la Cabeza."