Jasper

Physical Properties

Hardness: 6.5–7 on Mohs scale; Color: Brown, tan, reddish-orange with variegated patterns; Luster: Vitreous to waxy (when polished); Crystal Structure: Hexagonal/Trigonal (microcrystalline); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.58–2.91.

Formation & Geological History

Formed through the deposition of silica from water or hydrothermal fluids into sediments or volcanic ash. The organic or inorganic impurities create the distinct opaque banding and colors. Typically forms in sedimentary environments or hydrothermal veins.

Uses & Applications

Used primarily in lapidary arts for jewelry (cabochons, beads), decorative carvings, polished palm stones for collecting, and historically as tools/points due to its durability and hardness.

Geological Facts

Jasper has been used by humans for thousands of years; it was a favorite gemstone in the ancient world for talismans and cylinder seals. The term comes from the Greek 'iaspis', meaning 'spotted stone'.

Field Identification & Locations

Identify in the field by its opacity (unlike translucent agate), typical conchoidal fracture (curved, glass-like breaks), and high hardness—it will easily scratch glass but cannot be scratched by a steel knife. Common in riverbeds and coastal areas.

Identified on: 4/22/2026

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