sedimentary

Chert (Jasper)

Microcrystalline Quartz (SiO2)

Hardness: 6.5-7 Mohs; Color: Brown, tan, and reddish-brown; Luster: Dull to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 6
Color: Brown, tan, and reddish-brown
Luster: Dull to waxy

Identified July 20, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Brown, tan, and reddish-brown; Luster: Dull to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed from the accumulation of silica-rich organic remains or chemical precipitation in marine or groundwater environments. This water-worn pebble has been smoothed by fluvial or lacustrine action.

Uses & applications

Historically used for stone tools due to sharp edges; currently used for decorative gravel, landscaping, and as a lapidary material for tumbling.

Geological facts

Chert and jasper have been used by humans for hundreds of thousands of years to create arrowheads and scrapers. The reddish tint in this specimen suggests the presence of iron oxide (hematite).

Field identification & locations

Identify by its hardness (it will scratch glass), smooth texture, and characteristic curved (conchoidal) breaks. This specimen was likely found in a riverbed or on a beach.