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.
Where to Find Smoky Quartz
RockHoundR, the free-to-download rockhounding map from the Ruby Glint team, shows where collectors find smoky quartz in the US, with land-access notes for BLM land and national forests. Collecting is banned in national parks.
See where to find smoky quartzAlways check the local rules and get the landowner's permission before you collect.
Quick Facts
Physical Properties
- Color
- Brown, Gray, Black
- Hardness (Mohs)
- 7
- Rock tumbling
- With care
- Density
- 2.65 g/cm³
- Streak
- White
Chemical Properties
- Chemical Formula
- SiO2
- Elements
- Silicon, Oxygen
Also Known As
Identify Smoky Quartz Instantly
- Snap a photo, get instant results
- 6,700+ rocks, minerals & crystals
- Discover collecting spots near you
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.