Crystalline Quartz Buying Guide
Although often overlooked, quartz is available in many styles at reasonable prices. Our crystalline quartz buying guide can help you pick your…
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
Data | Value |
---|---|
Name | Smoky Quartz |
Is a Variety of | Quartz |
Varieties | Morion |
Crystallography | Hexagonal (trigonal) |
Refractive Index | 1.544-1.553 |
Colors | Every shade of brown. |
Hardness | 7 |
Wearability | Very Good |
Fracture | Conchoidal to uneven |
Birefringence | 0.009 |
Cleavage | None or indistinct |
Dispersion | 0.013 |
Absorption Spectrum | Not diagnostic. |
Pleochroism | Dark stones: weak brown/reddish brown. Light stones: weak, light and darker yellowish brown. |
Optics | o = 1.544; e = 1.553 (very constant). Uniaxial (+). |
Optic Sign | Uniaxial + |
Luster | Vitreous. |
Polish Luster | Vitreous. |
Fracture Luster | Vitreous. |
Specific Gravity | 2.651 |
Enhancements | Heating (occasional). |
Typical Treatments | Heat Treatment |
Transparency | Transparent to opaque. |
Comments
Smoky quartz is also mistaken for topaz. It comes in every shade of brown, from a light tan to nearly black. “Chocolate citrine” is a pleasant brownish/yellow color. Smoky quartz is known for its large sizes. The person who wants a really big gem, without a really big budget, often ends up with one of these.
Sources
Stone Sizes
Smoky quartz: is in the same size league as citrine, but larger stones get very dark and opaque. Smithsonian Institution (Washington, D.C): 4500 (California) and 1695 (Brazil), plus others.