mineral

Smoky Quartz (Tumbled)

Silicon Dioxide (SiO2)

Hardness: 7.0 on Mohs scale; Color: Grayish-brown, translucent to transparent; Luster: Vitreous (glassy); Crystal Structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7
Color: Grayish-brown, translucent to transparent
Luster: Vitreous (glassy)

Identified March 26, 2026More mineral →

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Physical properties

Hardness: 7.0 on Mohs scale; Color: Grayish-brown, translucent to transparent; Luster: Vitreous (glassy); Crystal Structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed in igneous and metamorphic rocks, particularly pegmatites and hydrothermal veins. The smoky color is caused by natural gamma radiation from the surrounding rock that interacts with trace aluminum impurities in the quartz over millions of years.

Uses & applications

Used primarily in jewelry (faceting and beads), decorative ornaments, and by metaphysical collectors. In industry, high-purity quartz is used in electronics and glass manufacturing.

Geological facts

Smoky Quartz is the national gem of Scotland, where it is known as 'Cairngorm.' It was used for sunglasses in 12th century China, where flat panes of the mineral were used to shield the eyes.

Field identification & locations

Identify by its smoky gray/brown color and glassy appearance. To differentiate from obsidian, check for its superior hardness (cannot be scratched by a steel nail). Commonly found in the Swiss Alps, Brazil, and the United States (Colorado).