mineral

Banded Calcite

Calcite (Calcium Carbonate - CaCO3)

Hardness: 3 on Mohs scale; Color: Cream, white, and translucent with dark grey/black carbonaceous bands; Luster: Vitreous to pearly; Crystal structure: Trigonal/Rhombohedral; Cleavage: Perfect rhombohedral in three directions; Specific gravity: 2.71

Hardness: 3 on Mohs scale
Luster: Vitreous to pearly

Identified June 2, 2026More mineral →

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Physical properties

Formation & geological history

Formed through chemical precipitation from calcium-rich solutions. This specimen likely formed in a hydrothermal vein or as a flowstone deposit in a cave system where alternating mineral concentrations created the distinct dark and light banding.

Uses & applications

Primarily used as decorative stone, for metaphysical or collection purposes, and historically in cement manufacturing or as a soil conditioner in agricultural lime.

Geological facts

Calcite is one of the most common minerals on Earth and is the primary constituent of limestone and marble. It exhibits double refraction (birefringence) and will effervesce (fizz) vigorously when in contact with dilute hydrochloric acid.

Field identification & locations

Identify in the field by its softness (can be scratched by a copper coin/penny) and its reaction to acid. Often found in limestone quarries, cave environments, and areas with significant hydrothermal activity. Banded varieties are frequently called 'onyx' in the decorative trade, despite being calcite.