mineral

Smoky Quartz

Smoky Quartz (Silicon Dioxide - SiO2)

Hardness: 7 (Mohs scale); Color: Brownishly-grey to black; Luster: Vitreous (glassy); Crystal structure: Trigonal (hexagonal prisms); Cleavage: None; Specific gravity: 2.65

Hardness: 7 (Mohs scale)
Color: Brownishly-grey to black
Luster: Vitreous (glassy)

Identified April 11, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: Brownishly-grey to black; Luster: Vitreous (glassy); Crystal structure: Trigonal (hexagonal prisms); Cleavage: None; Specific gravity: 2.65

Formation & geological history

Formed in igneous or metamorphic rocks via hydrothermal processes. The distinctive color results from natural irradiation of aluminum-bearing quartz over geological time (Cenozoic to Precambrian).

Uses & applications

Used in jewelry (gemstones), decorative carvings, precision oscillators (electronics), and frequently collected by mineral enthusiasts.

Geological facts

Smoky quartz can range from nearly translucent to an opaque black variety known as 'Morion.' It is the national gem of Scotland, where it is often called 'Cairngorm.'

Field identification & locations

Identify in the field by its hardness (will scratch glass), conchoidal (shell-like) fracture, and glassy luster. Often found in granite pegmatites and alpine-type fissures.