Jasper

Physical Properties

Hardness: 6.5-7 (Mohs); Color: Red, yellow, brown, and cream mottled patterns; Luster: Dull to greasy; Crystal Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91

Formation & Geological History

Forms through the deposition of silica from water deep within the earth or in marine sediments. The intense colors are caused by impurities such as iron oxides (hematite and goethite) and manganese. It is often found in prehistoric sedimentary formations.

Uses & Applications

Primary use in lapidary work for making cabochons, beads, and ornamental carvings. Historically used for making tools due to its conchoidal fracture which produces sharp edges.

Geological Facts

Jasper was a favorite gem in the ancient world, mentioned in many cultural mythologies and religious texts as a protective stone. The name 'Jasper' is derived from the Greek word 'iaspis', meaning spotted stone.

Field Identification & Locations

Identify in the field by its hardness (it can scratch glass), its opaque nature, and the smooth, curved (conchoidal) surface where it has broken. Commonly found in riverbeds, gravel pits, and volcanic regions.

Identified on: 4/27/2026

Mode: Standard