mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Brownish-gray to black; Luster: Vitreous (glass-like); Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Brownish-gray to black
Luster: Vitreous (glass-like)

Identified March 15, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Brownish-gray to black; Luster: Vitreous (glass-like); Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Forms in igneous rocks like granite or metamorphic rocks. The dark color is caused by natural radiation from surrounding rock or aluminum impurities during crystallization. Common throughout many geological eras.

Uses & applications

Used widely in lapidary for gemstones and jewelry. Industrial uses include glassmaking and electronics (though replaced mostly by synthetic quartz), and it is highly popular for decorative home decor and mineral collections.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm'. Some specimens can be nearly opaque black, known as 'Morion'.

Field identification & locations

Identify by its smoky translucence, lack of cleavage, and sharp conchoidal (shell-like) fractures. Found commonly in mountainous regions or inside pegmatites. Collectors look for well-defined crystal points or terminations.