Opal-CT (variety lussatite) after fossil (Helix ramondi)

Les Rois Mine, Mur-sur-Allier, Pont-du-Château, Clermont-Ferrand District, Puy-de-Dôme Department, Auvergne-Rhône-Alpes  France

Specimen size: 5.3 × 4.7 × 2 cm = 2.09” × 1.85” × 0.79”
Main crystal size: 2 × 1.6 cm = 0.79” × 0.63”