sedimentary (secondary classification: cryptocrystalline quartz)

Jasper pebble

Silicon dioxide (SiO2) with iron oxide inclusions

Hardness: 6.5–7 on Mohs scale. Color: Reddish-brown to maroon due to hematite/iron content. Luster: Dull to waxy when unpolished. Structure: Cryptocrystalline. Cleavage: None (conchoidal fracture). Specific gravity: 2.58–2.91.

Hardness: 6
Color: Reddish-brown to maroon due to hematite/iron content
Luster: Dull to waxy when unpolished

Identified March 24, 2026More sedimentary (secondary classification: cryptocrystalline quartz) →

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Physical properties

Formation & geological history

Formed from the deposition of silica in fluid-rich environments, often near volcanic ash or in sedimentary beds where silica-rich fluids permeate porous ground. The color comes from iron impurities during its millions of years of formation.

Uses & applications

Commonly used in lapidary work, jewelry (cabochons), river rock landscaping, and as a 'pocket stone' for collectors.

Geological facts

Jasper has been used since antiquity as a gemstone. The word is derived from the Greek 'iaspis', meaning 'spotted stone.' Many cultures believed it had protective properties and helped ground the wearer.

Field identification & locations

Identify in the field by its opacity (it will not let light through even when thin) and its smooth, rounded texture in riverbeds. Found globally in river wash and gravel deposits. Collectors look for unique patterns or deep, consistent colors.

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