The prehnites from the Roncari Quarry are quite distinctive. Instead of balls, they form radial cones, which remind me of bipyramidal quartz crystals. This piece has one large prehnite crystal which shows the morphology quite well. the specimen is a single calcite covered on the sides with prehnite while the top remains prehnite-free. The prehnite crystals in back are not complete, but this is a nice example from a quarry which is stilla ctive, but does not allow collecting. 5 x 4 x 5 cm.