Blue Calcite

Physical Properties

Hardness: 3 on Mohs scale; Color: Pale blue to sky 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, primarily from the shells of marine organisms or precipitation in hot springs and caves, and also found as a primary mineral in igneous and metamorphic rocks like marble.

Uses & Applications

Used in the manufacturing of cement and lime, as a soil conditioner in agriculture, in the optical industry for high-grade specimens, as decorative stones, and widely in the metaphysical/collecting community.

Geological Facts

Blue calcite is one of the most common minerals on Earth, but the distinct blue variety is specifically prized for its soothing color. It is highly reactive to cold dilute hydrochloric acid, producing immediate effervescence.

Field Identification & Locations

Identify by its sky-blue color, its softness (can be scratched by a copper penny or glass), and its distinctive rhombohedral cleavage. Large deposits are notably found in Mexico, Brazil, and Madagascar.

Identified on: 4/23/2026

Mode: Standard