sedimentary

Chert (Jasper)

Cryptocrystalline Quartz (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown, earthy orange; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7.

Hardness: 6
Color: Reddish-brown, earthy orange
Luster: Dull to waxy

Identified June 23, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown, earthy orange; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7.

Formation & geological history

Formed from the accumulation of silica-rich organic remains or chemical precipitation in sedimentary environments. Can be found in nodules or bedded deposits across various geological ages from Precambrian to Cenozoic.

Uses & applications

Used historically for stone tools and weapons due to its sharp fracture edges. Today it is used in landscaping, as a gemstone (Jasper), and as an abrasive in industrial manufacturing.

Geological facts

This specimen appears to be a weathered chert nodule, likely jasper. Jasper has been used by humans for over 4,000 years for seals and jewelry in civilizations like Mesopotamia.

Field identification & locations

Identify in the field by its hardness (will scratch glass), waxy luster when broken, and characteristic smooth, curved conchoidal fractures. Commonly found in riverbeds or limestone outcrops.