sedimentary

River Jasper (Green Jasper)

Silicon Dioxide (SiO2) with impurities

Hardness: 6.5–7 on Mohs scale; Color: Dark olive green with darker banding/streaks; Luster: Waxy to vitreous; Crystal structure: Microcrystalline (Trigonal); Cleavage: None (Conchoidal fracture); Specific gravity: 2.5–2.9.

Hardness: 6
Color: Dark olive green with darker banding/streaks
Luster: Waxy to vitreous

Identified April 28, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the infiltration of silica-rich fluids into sediment or volcanic ash. The green color is primarily due to silicate minerals like chlorite or iron inclusions. This specimen appears as a river-worn cobble, meaning it has been mechanically weathered and rounded by water transport over thousands of years.

Uses & applications

Used primarily for lapidary work, jewelry (cabochons), pocket stones, and decorative landscaping. High-quality pieces are used for carving.

Geological facts

Jasper is an opaque variety of chalcedony. The name comes from the Greek 'iaspis', meaning 'spotted stone.' It has been used by humans since antiquity for both tools and ornamentation.

Field identification & locations

Identify in the field by its opacity (unlike translucent agate), high hardness (cannot be scratched by a steel knife), and smooth, water-worn texture if found near riverbeds. Common in gravel deposits globally.

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