Crushed Limestone

Physical Properties

Hardness: 3 (Mohs scale). Color: White, light gray, or tan. Luster: Dull/earthy/vitreous. Crystal structure: Usually microcrystalline. Cleavage: Perfect rhombohedral in calcite crystals, though rarely visible in bulk rock. Specific gravity: 2.5-2.7.

Formation & Geological History

Formed through the accumulation of shell, coral, algal, and fecal debris in warm, shallow marine waters. Most commercially available crushed limestone dates from the Paleozoic or Mesozoic eras.

Uses & Applications

Massively used in construction as road base, concrete aggregate, railroad ballast, and for manufacturing cement. Also used in soil conditioning and as a source of industrial lime.

Geological Facts

Limestone makes up about 10% of the total volume of all sedimentary rocks. It is the primary ingredient in Portland cement and can contain fossils of ancient sea creatures.

Field Identification & Locations

Identify in the field by its light color and reaction to diluted hydrochloric acid (it will fizz). It is commonly found in quarries and as landscaping stone. For collectors, it is best found in outcrops where fossils might be preserved.

Identified on: 4/25/2026

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