Chert (Honey Chert / Flint)

Physical Properties

Hardness: 7 on Mohs scale; Color: Honey-yellow, brown, and tan with white rinds; Luster: Waxy to vitreous; Structure: Cryptocrystalline (crystals too small to see); Cleavage: None (has conchoidal fracture); Specific Gravity: 2.6+.

Formation & Geological History

Formed through the accumulation of silica-rich microfossils (like radiolarians or diatoms) or by chemical precipitation from silica-rich groundwater within limestone or chalk beds. Often Cretaceous or older in geological age.

Uses & Applications

Used historically for stone tools and weapons (arrowheads); currently used as a gemstone (cabochons), in landscape construction (road beds), and for fire-starting (flint and steel).

Geological Facts

Chert is so hard it can scratch steel. When struck, it breaks into very sharp edges, which is why it was the primary material for prehistoric survival tools.

Field Identification & Locations

Identify in the field by its smooth, waxy texture and shell-like (conchoidal) curved breaks. Often found as nodules within limestone outcrops or as river-worn pebbles. This specimen shows a 'chalky' cortex or weathering rind.

Identified on: 4/27/2026

Mode: Standard