Smoky Quartz

Physical Properties

Hardness: 7 on Mohs scale; Color: Grayish-brown, smoky, translucent; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & Geological History

Formed in igneous and metamorphic rocks, particularly pegmatites. The smoky color is caused by natural radiation from surrounding rocks activating aluminum impurities within the crystal lattice.

Uses & Applications

Used in jewelry, as gemstone specimens for collectors, and in some optical or electronic equipment though mostly replaced by synthetic quartz.

Geological Facts

The smoky color can be intensely dark (referred to as Morion) or light and yellowish. It is the national gem of Scotland, where it is often called Cairngorm after the mountain range where it is found.

Field Identification & Locations

Identify in the field by its distinct smoky gray-brown translucency and its ability to scratch glass easily. Commonly found in granite pegmatites and hydrothermal veins worldwide.

Identified on: 5/2/2026

Mode: Standard