Pont-du-Château, Clermont-Ferrand, Puy-de-Dôme, Auvergne-Rhône-Alpes, France
A 1,5cm sample of opal-CT from "pont de Dallet" We can easily see the layers that formed the specimen.
© Patrice Cmolik
A 3,5cm flower of quartz on chalcedony and opal-CT.
Old specimen with hand-written label showing translucent quartz crystals on matrix with small blue opal beads. Size: 60 x 55 mm Collection & photo: Alain TUEL
© Alain TUEL
White opal balls on matrix. Collection Museum of Natural Sciences, Barcelona, Spain. Photo Peter Lof, June 15, 2018, Barcelona.
© Peter Lof
