mineral
Blue glassy mineral fragment, possibly dyed/cobalt-colored calcite or aragonite
Uncertain from image; vivid blue coloration may indicate treated calcite (CaCO₃), aragonite (CaCO₃), or synthetic glass
AI-generated identification · may be incorrectBright cobalt-blue, translucent to opaque, vitreous-to-waxy luster, irregular fracture, and no visible crystal faces or cleavage. Apparent hardness is approximately Mohs 3–4 if calcite/aragonite; glass would be about 5–6.5.
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Physical properties
Bright cobalt-blue, translucent to opaque, vitreous-to-waxy luster, irregular fracture, and no visible crystal faces or cleavage. Apparent hardness is approximately Mohs 3–4 if calcite/aragonite; glass would be about 5–6.5.
Formation & geological history
If natural calcite or aragonite, it formed from carbonate-rich hydrothermal, cave, or sedimentary environments, generally much younger than the host sediment. The intense uniform blue may result from dye, coating, or laboratory treatment.
Uses & applications
Small pieces are sold as low-cost mineral specimens, craft material, or novelty stones; untreated blue calcite can be decorative, while dyed material has little gem value.
Geological facts
Blue calcite commonly shows cleavage and fizzes in dilute hydrochloric acid; aragonite is commonly fibrous or radiating. Color alone cannot distinguish these from blue glass or resin.
Field identification & locations
Check density, hardness, cleavage, and acid reaction on an inconspicuous area; a jeweler’s loupe may reveal bubbles or dye concentrations indicating glass or treatment. Common sources for blue calcite/aragonite include Mexico, Morocco, and China.
