Smoky Quartz

Physical Properties

Hardness: 7 on Mohs scale; Color: Pale yellowish-brown to grayish-black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & Geological History

Formed in igneous and metamorphic rocks, especially granites and pegmatites. The smoky color is caused by natural irradiation of aluminum-bearing quartz over millions of years.

Uses & Applications

Used in gemstone jewelry, ornamental carvings, and electronics (as oscillators). Also popular among collectors and for metaphysical practices.

Geological Facts

Smoky Quartz is the national gem of Scotland, where it has been mined since the 1830s in the Cairngorm Mountains and is often called 'Cairngorm stone'.

Field Identification & Locations

Identify by its hardness (scratches glass), lack of cleavage, and translucent brown to gray hue. Commonly found in mountainous regions with granitic outcrops.

Identified on: 4/24/2026

Mode: Standard