Smoky Quartz
Quartz var. Smoky Quartz · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typical habit is prismatic with hexagonal cross-sections
Mineral Group
Silicates (Tectosilicate subfamily)
Chemical Formula
SiO2 (with trace Al and natural irradiation)
Formation Process
Magmatic or hydrothermal. Most commonly forms in granitic pegmatites or hydrothermal veins from silica-rich fluids.
About This Crystal
A translucent to transparent variety of quartz characterized by its grey, brown, or black color. This specimen shows a vitreous to sub-metallic luster on its crystal faces with some internal fractures.
Physical Characteristics
Color: Brownish-grey; Streak: White; Cleavage: None (indistinct); Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Usually inert.
Optical Properties
Uniaxial positive; Refractive Index: 1.544-1.553; Birefringence: 0.009; Pleochroism: Weak to moderate in brown shades.
Hardness & Durability
Origin Region
Notable sources include Brazil, Switzerland (The Alps), Madagascar, and various US states like Colorado (Pikes Peak).
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; Highly stable under normal wearing conditions, though very high heat can fade the color.
Care & Maintenance
Clean with warm soapy water. Safe for ultrasonic cleaners unless there are significant inclusions. Avoid prolonged exposure to intense heat.
Rarity & Value
Common and widely available. Value depends on clarity and size. Darker specimens (Morion) or those with inclusions like rutile are highly prized by collectors.
Special Characteristics
Coloration is caused by natural irradiation of trace aluminum substituting for silicon in the crystal lattice. May contain phantom growth lines or inclusions.
Lore & History
Historically used in Scotland (Cairngorms) for jewelry and weapon handles. In folklore, it is considered a grounding stone that wards off negative energy.