sedimentary

Calcite (or Travertine / Limestone)

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale. Color: Beige, tan, white, and brownish gray. Luster: Dull to earthy. Crystal structure: Trigonal/Hexagonal. Cleavage: Perfect rhombohedral (when crystalline). Specific Gravity: ~2.71. Highly reactive with dilute hydrochloric acid (effervesces).

Hardness: 3 on Mohs scale
Color: Beige, tan, white, and brownish gray
Luster: Dull to earthy

Identified July 22, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed primarily in shallow marine environments, hot springs, or caves through chemical precipitation or accumulation of biogenic shell debris. Commonly found in sedimentary basins and karst topographies worldwide.

Uses & applications

Used extensively in construction as crushed stone, lime production, cement manufacturing, acid neutralization, soil conditioner in agriculture, and as decorative stone or mineral specimens.

Geological facts

Calcite is one of the most common minerals on Earth's surface. It reacts vigorously with mild acid (like vinegar), producing visible bubbles of carbon dioxide gas, which is its most famous diagnostic test.

Field identification & locations

Field identification relies on low Mohs hardness (scratched easily with a copper penny or steel nail) and strong effervescence when exposed to acid. Commonly collected from quarries, roadcuts, and karst landscapes.

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