Smoky Quartz
Silicon Dioxide (Quartz variety: Smoky) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically occurs as hexagonal prisms with pyramidal terminations; often found in massive or granular forms.
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2 (with trace Al3+ ions and natural radiation exposure)
Formation Process
Igneous and Metamorphic; typically forms in pegmatites and hydrothermal veins under high-pressure conditions.
About This Crystal
The specimen exhibits a dark brownish-gray color with a vitreous to greasy luster. It is translucent to nearly opaque in thicker sections, showing uneven, fractured surfaces typical of massive quartz.
Physical Characteristics
Color: Smoky brown to black; Streak: White; Cleavage: None; Fracture: Conchoidal to uneven; Specific Gravity: 2.65; Fluorescence: Generally inert.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009 (Low); Pleochroism: Weak to moderate in darker stones; Singly elective with circular polarization.
Hardness & Durability
Origin Region
Brazil, Switzerland (often called Morion), Madagascar, and various USA locations (Pikes Peak, Colorado).
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; Stability: Very stable, though color may fade if exposed to temperatures exceeding 200°C for long periods.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid prolonged exposure to direct, high-intensity sunlight which can cause color fading in some varieties.
Rarity & Value
Common; Value is determined by transparency and depth of color. Inexpensive but highly popular for decorative and jewelry use.
Special Characteristics
Natural irradiation of aluminum impurities replaces silicon atoms, creating the 'smoky' color centers; can contain rutile or tourmaline inclusions.
Lore & History
Historically used in China for some of the first sunglasses (using thin slabs). Conceptually associated with grounding and protection in traditional crystal lore.