sedimentary

Red Jasper with Fossils

Silicified Fossiliferous Jasper (Chert variant, SiO2)

Hardness: 6.5-7.0 (Mohs scale); Color: Brick red to deep red with mustard yellow patterns; Luster: Vitreous to dull; Crystal structure: Microcrystalline (trigonal); Cleavage: None; Specific Gravity: 2.58-2.91.

Hardness: 6
Color: Brick red to deep red with mustard yellow patterns
Luster: Vitreous to dull

Identified June 6, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the process of silicification, where silica-rich fluids replace the organic structure of organisms (often crinoids or algae) within a mudstone or siltstone host. These specimens typically originate from Paleozoic or Mesozoic era deposits.

Uses & applications

Used primarily in jewelry as beads and cabochons, lapidary arts, and as ornamental stones for collecting and meditation.

Geological facts

The red color is caused by the inclusion of iron oxides (hematite) during the mineralization process. This specific pattern is often referred to commercially as Snake Skin Jasper or Fossil Jasper because the inclusions resemble animal patterns or colonial organisms.

Field identification & locations

Identify by its characteristic red and yellow ovoid patterns, high hardness (will scratch glass), and weight. Common locations include Africa (South Africa), Australia, and the USA (California and Oregon). Collectors look for high contrast and clear fossil replacement patterns.

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Sandstone or Siltstone

Arenite (if sandstone)

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Sandstone

Arenite (primarily SiO2)

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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

Argillaceous sedimentary rock

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Sandstone

Arenite

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