sedimentary

Limestone with Chert

Calcium Carbonate (CaCO3) with Silica (SiO2) inclusions

AI-generated identification · may be incorrect

Hardness: 3 (limestone matrix) to 7 (chert nodules); Color: Grey, tan, and white; Luster: Dull to earthy; Structure: Biogenic or chemical sedimentary layering; Specific Gravity: 2.3-2.7

Hardness: 3 (limestone matrix) to 7 (chert nodules)
Color: Grey, tan, and white
Luster: Dull to earthy

Identified June 1, 2026More sedimentary →

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Physical properties

Hardness: 3 (limestone matrix) to 7 (chert nodules); Color: Grey, tan, and white; Luster: Dull to earthy; Structure: Biogenic or chemical sedimentary layering; Specific Gravity: 2.3-2.7

Formation & geological history

Formed in marine environments through the accumulation of shell, coral, and algal debris, often with secondary silica replacement forming chert nodules over millions of years.

Uses & applications

Construction material, production of cement, crushed stone for road base, and soil conditioner in agriculture.

Geological facts

Limestone is the primary source of lime used in making glass. It often contains fossils of ancient marine organisms that lived millions of years ago.

Field identification & locations

Identified by its grey color and reaction to dilute hydrochloric acid (it fizzes). Harder chert nodules within will scratch steel. Commonly found in karst landscapes and coastal cliffs.