Quartz after fossil

Quartz geodes outcrop, Valdematilla ravine, Tubilla del Agua, Comarca Valle del Rudrón, Burgos, Castile and León  Spain

Specimen size: 11.8 × 11.1 × 4.5 cm = 4.65” × 4.37” × 1.77”
Main crystal size: 6.3 × 6 cm = 2.48” × 2.36”