sedimentary

River Jasper

Silicon Dioxide (SiO2) with impurities

Hardness: 6.5-7 Mohs; Color: Olive green to yellow-tan with brownish iron-oxide veining; Luster: Waxy to dull (wet appearance is vitreous); Structure: Microcrystalline quartz; Cleavage: None (Conchoidal fracture).

Hardness: 6
Color: Olive green to yellow-tan with brownish iron-oxide veining
Luster: Waxy to dull (wet appearance is vitreous)

Identified July 4, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed primarily in sedimentary environments where silica-rich fluids permeate porous volcanic ash or sedimentary beds. This specific specimen has been water-shaped and smoothed by fluvial (river) erosion over many years.

Uses & applications

Used for lapidary work, tumbled stones, jewelry (cabochons), and as decorative aquarium or landscaping stones.

Geological facts

Jasper is an opaque variety of chalcedony. The veins seen in this specimen are often 'healed' fractures where secondary minerals like iron oxides or manganese have filled in over geological time.

Field identification & locations

Identified in the field by its smooth, river-worn texture, opacity (does not let light through), and high hardness—it will easily scratch glass but cannot be scratched by a steel knife. Common in gravel beds and riverbanks.

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Cone-in-cone structure (Limestone)

Cone-in-cone structure (Secondary Sedimentary Structure)

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Chert Breccia

Brecciated Chert (Microcrystalline Silica)

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Sandstone Grain

Clastic Sedimentary Rock Grain (SiO2 dominated)

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Shale or Slaty Mudstone

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Sandstone

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