sedimentary

Chert (Jasper variety)

Microcrystalline Quartz (SiO2)

Hardness: 6.5-7 (Mohs); Color: Olive green, brown, and yellow; Luster: Waxy to dull (greasy when wet); Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Hardness: 6
Color: Olive green, brown, and yellow
Luster: Waxy to dull (greasy when wet)

Identified July 13, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich microfossils (like radiolarians) or chemical precipitation in marine environments. The specimen shows river-worn rounding, indicating transport in a fluvial environment.

Uses & applications

Used historically for stone tools and weapons due to its sharp edges when fractured. Today used in lapidary work, decorative landscaping, and as a semi-precious gemstone in jewelry.

Geological facts

Green jasper gets its color from iron silicate inclusions. It was a highly prized 'fertility stone' in ancient cultures and is often called 'Green Jasper' in the gem trade.

Field identification & locations

Identify in the field by its hardness (cannot be scratched by a steel knife), waxy smooth texture, and smooth, rounded water-worn exterior in riverbeds or beaches. Commonly found in coastal areas and old river deposits.

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Sandstone or Siltstone

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Brown Sandstone (River Rock)

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Mudstone

Argillite / Siliciclastic sedimentary rock

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Cone-in-cone structure (Limestone)

Cone-in-cone structure (Secondary Sedimentary Structure)

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Sandstone Grain

Clastic Sedimentary Rock Grain (SiO2 dominated)

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Sandstone

Arenite (primarily SiO2)

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