mineral

Smoky quartz crystal fragment

Quartz, silicon dioxide (SiO₂), smoky variety

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent gray-brown color, vitreous luster, and hexagonal crystal structure. Quartz has no true cleavage, but commonly shows conchoidal fracture; the specimen appears naturally fractured or partly tumbled.

Identified September 12, 2026More mineral →

Explore Smoky quartz crystal fragment 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

Smoky quartz forms in hydrothermal veins, pegmatites, and cavities in granitic rocks, with irradiation-induced color from trace aluminum. Its age depends on the host rock, commonly ranging from Paleozoic to recent; the image alone cannot establish age.

Uses & applications

Used as a collector mineral, ornamental stone, and occasionally in jewelry; gem-quality smoky quartz is faceted or cabochon-cut.

Geological facts

The smoky color is typically produced when natural radiation activates aluminum defects in quartz. Heating can remove the color, while irradiation can sometimes deepen it.

Field identification & locations

Identify by its glassy luster, hardness, translucent smoky color, and lack of cleavage; quartz will scratch ordinary glass. Common localities include Brazil, Switzerland, the United States, Madagascar, and Scotland.