Smoky Quartz
Quartz var. Smoky Quartz (Beta-Quartz) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically occurs in hexagonal prisms with rhombohedral terminations; the beads shown are faceted round or rondelle shapes.
Mineral Group
Silicates (Tectosilicate subgroup of the Quartz group)
Chemical Formula
SiO2 (Silicon Dioxide with aluminum impurities and natural irradiation)
Formation Process
Found in pegmatites, hydrothermal veins, and volcanic cavities; the smoky color is caused by natural irradiation of trace aluminum in the crystal structure.
About This Crystal
Transparent to translucent grayish-brown to nearly black crystalline quartz. The beads in the image show a vitreous (glassy) luster and vary from light tea-colored to a deeper 'Cairngorm' brown, with some appearing potentially amethystine (light purple/smoky mix).
Physical Characteristics
Color: Smoky brown, gray, or black; Streak: White; Cleavage: None/Indistinct; Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Generally inert under UV light.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009; Optical Character: Uniaxial (+); Pleochroism: Weak to distinct in shades of brown.
Hardness & Durability
Origin Region
Brazil (Minas Gerais), Madagascar, Switzerland (Alps), USA (Colorado - Pikes Peak), and Scotland.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; Stability: Stable to light, but may fade if heated to high temperatures (turning yellow/colorless).
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid steam cleaning or ultrasonic cleaners if inclusions are present. Store away from harder stones like diamonds to prevent scratching.
Rarity & Value
Common; Value is determined by clarity and depth of color. Usually inexpensive; often naturally occurring but can also be produced by artificially irradiating clear quartz.
Special Characteristics
May contain 'phantom' growth layers, rutilated inclusions, or fluid-filled cavities (enhydros). Occasionally shows asterism if inclusions are oriented correctly.
Lore & History
Historically used in China for the earliest sunglasses in the 12th century. Known as the national gem of Scotland (Cairngorm). Metaphysically associated with grounding, protection from negative energy, and the Root Chakra.