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 (±2015)

Specimen size: 10.6 × 7.1 × 6.6 cm = 4.17” × 2.80” × 2.60”
Main crystal size: 2 × 1.9 cm = 0.79” × 0.75”