sedimentary

Chert (Jasper variety)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs), Color: Reddish-brown, tan, and gray, Luster: Waxy to dull, Crystal Structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7

Hardness: 6

Identified June 4, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs), Color: Reddish-brown, tan, and gray, Luster: Waxy to dull, Crystal Structure: Trigonal (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 marine or groundwater environments. This specimen shows significant rounding due to water transport in a river or coastal setting.

Uses & applications

Historically used for making stone tools (arrowheads). Modern uses include landscaping, lapidary work, jewelry (when highly colorful), and industrial abrasives.

Geological facts

The red coloring in this jasper-like chert is typically caused by iron inclusions (hematite). It is one of the most durable sedimentary rocks and can survive millions of years of erosion.

Field identification & locations

Identify by its hardness (it will scratch glass), its smooth waxy feel when wet, and its characteristic curved (conchoidal) fracture planes. Common in riverbeds and glacial tills worldwide.