sedimentary
Calcite on Limestone (or Fossil)
Calcium Carbonate (CaCO3)
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
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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.
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