mineral

Smoky quartz crystal

Quartz, SiO₂; likely smoky quartz, possibly coated or included

AI-generated identification · may be incorrect

Mohs hardness 7; translucent gray-brown color, vitreous luster, hexagonal crystal structure, and no true cleavage but conchoidal fracture. The strong parallel striations and glassy surfaces are consistent with quartz, though the specimen appears partly fractured or polished.

Identified September 1, 2026More mineral →

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Physical properties

Formation & geological history

Forms in silica-rich hydrothermal veins, pegmatites, and cavities in igneous rocks; smoky coloration commonly results from natural irradiation of aluminum-bearing quartz. Exact age depends on locality, commonly Paleozoic to younger.

Uses & applications

Used as a collector specimen and occasionally as a gemstone; quartz is also important in glass, electronics, abrasives, and engineered stone.

Geological facts

Quartz commonly forms six-sided prisms with pyramidal terminations, while its fractures can produce sharp, irregular edges and curved conchoidal surfaces.

Field identification & locations

Look for hardness sufficient to scratch glass, lack of cleavage, hexagonal growth, and white streak; smoky quartz is common in Brazil, Switzerland, Madagascar, the United States, and worldwide. Identification from the photograph is provisional because the piece may be modified or coated.