sedimentary

Calcite on Limestone (or Fossil)

Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: honey-yellow to white/clear; Luster: Vitreous to pearly; Crystal structure: Trigonal/Rhombohedral; Cleavage: Perfect rhombohedral.

Hardness: 3 on Mohs scale
Color: honey-yellow to white/clear
Luster: Vitreous to pearly

Identified April 5, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: honey-yellow to white/clear; Luster: Vitreous to pearly; Crystal structure: Trigonal/Rhombohedral; Cleavage: Perfect rhombohedral.

Formation & geological history

Formed through chemical precipitation in marine environments or groundwater seepage within sedimentary rock cavities. This specimen often forms in vugs (small cavities) or within hollowed-out fossil shells over thousands to millions of years.

Uses & applications

A primary component in cement and lime production for construction. High-quality dogtooth or honey calcite is used as mineral specimens for collectors. Sometimes used as a flux in steel making.

Geological facts

Calcite is famous for its double refraction properties. It is one of the most common minerals on Earth, yet it can form in over 800 different crystal habits.

Field identification & locations

Identify in the field by its 3-way cleavage and the 'acid test'—it will effervesce (fizz) vigorously when touched with a drop of cold dilute hydrochloric acid or vinegar.