sedimentary

Coquina Jasper

Fossiliferous Chalcedony (SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Tan, yellow, reddish-brown fragments in a dark matrix; Luster: Vitreous to waxy after polishing; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.65

Hardness: 6
Color: Tan, yellow, reddish-brown fragments in a dark matrix
Luster: Vitreous to waxy after polishing

Identified March 24, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the fossilization of ancient marine shells and debris, which were eventually buried and replaced or cemented by silica-rich groundwater. Most deposits are approximately 65 to 145 million years old (Cretaceous period).

Uses & applications

Primarily used in lapidary arts for cabochons, carvings, and jewelry. Used by collectors for its unique 'script' patterns. Historically, the softer limestone variant was used in construction.

Geological facts

Also known as 'Script Stone', 'Elephant Skin Jasper', or 'Mariam Stone'. The unique patterns are actually fossilized shells and shell fragments that resemble ancient calligraphy or script.

Field identification & locations

Identify in the field by its distinct bioclastic texture where fragments of shells are visible but the rock is nearly as hard as glass. Commonly found in the Himalayan mountains of India and parts of Alabama, USA.