mineral

Smoky Quartz (Vein Quartz)

Quartz (Silicon Dioxide, SiO2)

Hardness: 7 (Mohs scale); Color: Gray to brownish-black, translucent; Luster: Vitreous (glassy); Crystal Structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 (Mohs scale)
Color: Gray to brownish-black, translucent
Luster: Vitreous (glassy)

Identified April 5, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: Gray to brownish-black, translucent; Luster: Vitreous (glassy); Crystal Structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Formation & geological history

Formed from silica-rich hydrothermal fluids cooling in veins or cavities within igneous or metamorphic host rocks. The smoky color is caused by natural gamma radiation from the surrounding rock acting on trace impurities of aluminum within the crystal lattice.

Uses & applications

Used primarily as a decorative stone, in lapidary work for jewelry and carvings, and as a collector's specimen. High-purity quartz is also used in electronics and glass-making.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as Cairngorm. Larger specimens like this one are often found in pegmatites and can weigh hundreds of pounds.

Field identification & locations

Identify by its hardness (scratches glass), glassy luster, and the characteristic 'smoky' translucency. It lacks cleavage planes, breaking instead like thick glass (conchoidal fracture). Common in mountainous, granitic terrains.

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