sedimentary

Red Jasper (River Pebble)

Jasper (Silicon Dioxide, SiO2)

Hardness: 6.5-7.0 on Mohs scale; Color: Reddish-brown with tan/yellow mottling; Luster: Vitreous to waxy (especially when wet); Crystal Structure: Microcrystalline silicon dioxide (cryptocrystalline quartz); Cleavage: None; Specific Gravity: 2.58-2.91

Hardness: 6
Color: Reddish-brown with tan/yellow mottling
Luster: Vitreous to waxy (especially when wet)

Identified May 21, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed as a result of the deposition of silica from water solutions into cracks or cavities of other rocks. Its red color comes from iron inclusions (hematite). This specimen shows rounding and smoothing due to fluvial (river) transport and erosion.

Uses & applications

Used primarily for ornamental purposes, jewelry (cabochons), lapidary art, and as decorative gravel in landscaping. Historically used for making tools due to its conchoidal fracture.

Geological facts

Jasper is an opaque variety of chalcedony. It has been used as a gemstone since antiquity and is mentioned in many historical texts, including the Bible. The name comes from the Greek word 'iaspis', meaning spotted stone.

Field identification & locations

Identify by its opacity (even on thin edges), hardness that can scratch glass, and lack of visible crystalline structure. Commonly found in riverbeds, glacial deposits, and gravel pits globally.

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