mineral
Chalcanthite (Likely Synthetic/Lab-Grown)
Hydrated copper(II) sulfate (CuSO4·5H2O)
Hardness: 2.5 (Mohs scale); Color: Neon deep blue; Luster: Vitreous to resinous; Crystal structure: Triclinic; Cleavage: Imperfect; Specific gravity: 2.2-2.3. Note: The specimen in the image has a matte, light-blue coating or paint on top of natural-looking dark blue crystals.
- Hardness
- 2
- Color
- Neon deep blue
- Luster
- Vitreous to resinous
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Physical properties
Hardness: 2.5 (Mohs scale); Color: Neon deep blue; Luster: Vitreous to resinous; Crystal structure: Triclinic; Cleavage: Imperfect; Specific gravity: 2.2-2.3. Note: The specimen in the image has a matte, light-blue coating or paint on top of natural-looking dark blue crystals.
Formation & geological history
Natural chalcanthite is a secondary mineral formed in oxidation zones of copper deposits. However, large, cluster-like specimens like this are almost exclusively laboratory-grown crystals created by evaporating a copper sulfate solution over a natural rock matrix.
Uses & applications
Primarily used for decorative display and mineral collecting. Industrially, copper sulfate is used as a pesticide, fungicide, and in battery electrolytes.
Geological facts
Chalcanthite is water-soluble; if you place it in water, it will dissolve. It is also toxic if ingested and can cause skin irritation due to its copper content. Most 'large' clusters found in shops are adult-made 'lab-grown' specimens rather than mine-extracted.
Field identification & locations
Identify in the field by its brilliant blue color and soluble nature. It is often found in arid regions where it won't be washed away by rain. For collectors, handle with gloves and keep in a dry, airtight container to prevent dehydration (efflorescence).
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