Blue Calcite

Physical Properties

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

Formation & Geological History

Formed through sedimentary processes or as a secondary mineral in igneous and metamorphic rocks. It often precipitates from hydrothermal solutions or forms in marine environments where calcium carbonate accumulates.

Uses & Applications

Used primarily as decorative carvings, ornamental stones, and highly favored and collected by mineral enthusiasts. In industrial forms, calcite is used in cement, antacids, and soil conditioners.

Geological Facts

Calcite is one of the most common minerals on Earth. The blue variety specifically is often 'acid-washed' by dealers to give it a smooth, waxy feel and to highlight its color for collectors.

Field Identification & Locations

Identified in the field by its softness (can be scratched by a copper coin) and its strong reaction (effervescence) when exposed to dilute hydrochloric acid. Look for distinct rhombohedral cleavage planes.

Identified on: 5/3/2026

Mode: Standard