mineral

Blue Calcite

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale; Color: Pale blue to sky blue; Luster: Vitreous to pearly; Crystal structure: Trigonal/Rhombohedral; Cleavage: Perfect rhombohedral in three directions; Specific gravity: 2.71

Hardness: 3 on Mohs scale
Color: Pale blue to sky blue
Luster: Vitreous to pearly

Identified June 22, 2026More mineral →

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Physical properties

Formation & geological history

Formed through sedimentary processes, often as a chemical precipitate from calcium-rich waters or in marine environments. It can also form in hydrothermal veins and metamorphic marbles.

Uses & applications

Used primarily as decorative carvings, ornamental stones, and in the lapidary arts. Calcium carbonate in general is used in agriculture, construction (as limestone/marble), and as a ph neutralizer.

Geological facts

Blue Calcite is very soft and can be scratched by a copper coin. It reacts and fizzes when it comes into contact with even weak acids like vinegar. It is one of the most common minerals on Earth but the sky-blue variety is specific to a few regions.

Field identification & locations

Identify by its waxy feel, rhombohedral cleavage planes, and pale blue color. Most commonly found in large deposits in Madagascar and Mexico. Collectors should look for vibrant color and lack of white bruising.