mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale. Color: Translucent to semi-opaque smoky brown, grey, or blackish. Luster: Vitreous (glassy). Crystal Structure: Hexagonal (trigonal). Cleavage: None, conchoidal fracture. Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Translucent to semi-opaque smoky brown, grey, or blackish
Luster: Vitreous (glassy)

Identified July 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed in pegmatites, hydrothermal veins, and metamorphic rocks. The distinct brown to grey smoky color is produced by natural underground radiation exposing traces of aluminum within the quartz crystal lattice.

Uses & applications

Used extensively in jewelry, ornamental carvings, lapidary art, and metaphysical crystal collections. Clear gem-quality pieces are faceted into gemstones.

Geological facts

The smoky color can fade if exposed to prolonged high heat or intense direct sunlight over extended periods. Smoky quartz is the national gem of Scotland, where it is known as Cairngorm.

Field identification & locations

Identified by its glass-like vitreous luster, conchoidal fracture, hardness of 7 (will scratch glass), and translucent brown/grey hue. Commonly found in granite pegmatites, river gravels, and mountainous regions worldwide (e.g., Brazil, USA, Madagascar, the Alps).