mineral

Smoky quartz crystal

Quartz, silicon dioxide (SiO₂), brown variety colored by irradiation and trace aluminum

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent smoky-brown color, vitreous luster, hexagonal prismatic crystal with pyramidal termination, and no true cleavage (conchoidal fracture). The specimen appears naturally terminated but may have minor surface damage or polishing.

Identified September 14, 2026More mineral →

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Physical properties

Formation & geological history

Forms in silica-rich hydrothermal veins, pegmatites, and cavities in igneous rocks; crystals may range from modern geological growth to hundreds of millions of years old. Exact age and locality cannot be determined from the photograph.

Uses & applications

Used as a collector mineral, ornamental stone, and occasionally in jewelry; large transparent crystals are especially desirable.

Geological facts

Smoky coloration results primarily from radiation-induced color centers associated with trace aluminum. Heating can remove the brown color, while irradiation can produce it in some quartz.

Field identification & locations

Identify by its glassy luster, hexagonal prism, pointed termination, conchoidal fracture, and ability to scratch glass; unlike smoky glass, it commonly shows natural crystal faces and internal inclusions. Common sources include Brazil, Switzerland, Madagascar, the United States, and Scotland.