mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: Brownish grey to black; Luster: Vitreous; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 (Mohs scale)
Color: Brownish grey to black
Luster: Vitreous

Identified July 21, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: Brownish grey to black; Luster: Vitreous; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Forms in igneous rocks like pegmatites and granites, or in metamorphic rocks. The brown color is caused by natural irradiation of silicon dioxide crystals containing trace amounts of aluminum.

Uses & applications

Used widely in lapidary for jewelry, gemstones, decorative carvings, and as a popular collector's mineral specimen.

Geological facts

The dark brown or black variety is often called Morion. It is the national gem of Scotland, where it is known as Cairngorm after the mountain range where it was historically found.

Field identification & locations

Identify by its characteristic conchoidal fracture (curved glass-like breaks) and translucent brown tint. Found globally in mountainous regions and riverbeds.