mineral

Blue calcite (probable)

Calcite, calcium carbonate (CaCO₃)

AI-generated identification · may be incorrect

Pale blue, translucent-to-opaque rough crystalline specimen with vitreous to pearly luster and prominent rhombohedral cleavage; Mohs hardness 3, specific gravity about 2.71. The blue color commonly comes from trace impurities or structural defects.

Identified August 9, 2026More mineral →

Explore Blue calcite (probable) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Forms when calcium-rich groundwater or hydrothermal fluids precipitate carbonate, commonly in veins, cavities, and sedimentary limestone environments. It may range from ancient to geologically recent; the photograph cannot establish age or locality.

Uses & applications

Used chiefly as a collector mineral and ornamental stone; calcite is also important industrially for cement, lime, aggregate, optical instruments, and chemical applications.

Geological facts

Calcite strongly effervesces with dilute hydrochloric acid and exhibits birefringence, producing doubled images when viewed through clear pieces. Blue calcite is generally more fragile and softer than quartz or feldspar.

Field identification & locations

Confirm with a hardness test against a copper coin or steel knife and an acid fizz test on a concealed spot; cleavage surfaces and rhombohedral shape support identification. Common localities include Mexico, Brazil, the United States, and Madagascar.