mineral
Calcite
Calcium Carbonate (CaCO3)
Hardness: 3 on Mohs scale; Color: White/off-white; Luster: Vitreous to pearly; Crystal structure: Trigonal/Rhombohedral cleavage; Cleavage: Perfect rhombohedral in three directions; Specific gravity: 2.71
- Hardness
- 3 on Mohs scale
- Color
- White/off-white
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 3 on Mohs scale; Color: White/off-white; Luster: Vitreous to pearly; Crystal structure: Trigonal/Rhombohedral cleavage; Cleavage: Perfect rhombohedral in three directions; Specific gravity: 2.71
Formation & geological history
Formed through sedimentary precipitation in marine environments, hydrothermal veins, or as a constituent of metamorphic marble. It is the primary mineral in limestone and marble.
Uses & applications
Used in the manufacture of cement and mortar, as a soil conditioner in agriculture, a flux in glassmaking, and clear varieties (Iceland Spar) are used in optical instruments.
Geological facts
Calcite is famous for its double refraction (birefringence), where an object viewed through a clear crystal appears doubled. It is the primary component of stalactites and stalagmites in caves.
Field identification & locations
Identify in the field by its 3-way rhombohedral cleavage and its strong effervescence (bubbling) when exposed to cold dilute hydrochloric acid or vinegar. Common worldwide, especially in limestone regions.
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Schist
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Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
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Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic