Smoky Quartz
What is Smoky Quartz?
Smoky Quartz is a brownish-gray to black, translucent variety of quartz. It owes its color to natural irradiation, which causes the presence of aluminum impurities within the crystal lattice. The depth of color varies from nearly transparent to opaque black, depending on the intensity of the irradiation and the concentration of impurities. It is a relatively common gemstone, prized for its clarity and smoky appearance.
Optical Properties
- Refractive Index
- 1.544-1.553
- Birefringence
- 0.009
- Pleochroism
- Weak to distinct
- Optical Character
- uniaxial (+)
- Dispersion
- 0.013
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Smoky Quartz before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Smoky Quartz Localities Map
See where Smoky Quartz is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Quick Facts
Physical Properties
- Color
- Brown, Gray, Black
- Hardness (Mohs)
- 7
- Density
- 2.65 g/cm³
- Streak
- White
Chemical Properties
- Chemical Formula
- SiO2
- Elements
- Silicon, Oxygen
Also Known As
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Smoky Quartz FAQs
How do I identify Smoky Quartz?
Smoky Quartz can be identified by its hardness of 7 on the Mohs scale, Brown color. Look for these key characteristics when examining specimens.
What color is Smoky Quartz?
Smoky Quartz typically appears in Brown, Gray, Black. Color can vary depending on impurities and formation conditions.
How hard is Smoky Quartz?
Smoky Quartz has a hardness of 7 on the Mohs scale. This makes it a relatively hard mineral suitable for jewelry.