sedimentary

Chert (or Chalcedony)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale. Color: Tan, beige, or off-white with a waxy to dull luster. Structure: Microcrystalline with conchoidal fracture. Opaque to translucent.

Hardness: 7 on Mohs scale
Color: Tan, beige, or off-white with a waxy to dull luster

Identified July 1, 2026More sedimentary →

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Physical properties

Hardness: 7 on Mohs scale. Color: Tan, beige, or off-white with a waxy to dull luster. Structure: Microcrystalline with conchoidal fracture. Opaque to translucent.

Formation & geological history

Formed primarily by the chemical precipitation of silica-rich fluids in sedimentary environments. Often occurs as nodules or layers within limestone or chalk formations. Many specimens date from the Paleozoic or Mesozoic eras.

Uses & applications

Historically used for stone tools (arrowheads, scrapers) due to its sharp conchoidal edges; currently used for road aggregate and as an ornamental stone in landscaping.

Geological facts

Chert is essentially the same material as flint, though 'flint' is usually used for darker varieties found in chalk. It is one of the most durable rocks, often surviving long-term weathering that dissolves surrounding limestone.

Field identification & locations

Identify in the field by its hardness (will scratch glass), waxy texture, and shell-like (conchoidal) breaking pattern. Found worldwide in riverbeds and limestone outcrops.