Chert (Honey Chert or Chalcedony Pebble)

Physical Properties

Hardness: 6.5-7 (Mohs); Color: Waxy brown, honey-yellow, tan; Luster: Vitreous to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.65

Formation & Geological History

Formed through the accumulation of silica-rich microfossils (like radiolarians or diatoms) or by chemical precipitation in marine or groundwater environments. This specimen appears water-worn, likely from a river or glacial deposit.

Uses & Applications

Historically used for making stone tools (flint knapping) due to its sharp edges; used today as decorative river rock, landscaping, or as tumbled stones for hobbyists.

Geological Facts

Chert is incredibly durable and resistant to chemical weathering. It was one of the most important minerals for early humans, used for arrowheads, scrapers, and fire-starting (flint is a variety of chert).

Field Identification & Locations

Identify in the field by its waxy texture and conchoidal (shell-shaped) fracture marks. It will scratch glass but cannot be scratched by a steel knife. Common in gravel pits and riverbeds.

Identified on: 4/16/2026

Mode: Standard