sedimentary

Chert (Jasper/Chalcedony)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs); Color: Tanish-brown/honey; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture)

Hardness: 6
Color: Tanish-brown/honey
Luster: Waxy to vitreous

Identified July 6, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Tanish-brown/honey; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture)

Formation & geological history

Forms primarily as a biochemical sedimentary rock by the accumulation of siliceous remains or as a chemical precipitate replacing limestone or dolostone. Common in prehistoric seafloor deposits.

Uses & applications

Historically used for stone tools (knapping) due to its sharp edges; used today as a decorative stone and in landscaping.

Geological facts

This specimen displays a distinct conchoidal (shell-like) fracture pattern, which is why it was the primary material for arrowheads and scrapers during the Stone Age.

Field identification & locations

Identified in the field by its hardness (cannot be scratched by a steel nail), waxy luster, and smooth, curved fracture surfaces. Found worldwide in nodules or bedded layers.