mineral
Smoky Quartz / Chalcedony
Silicon Dioxide (SiO2)
Hardness: 6.5-7 on Mohs scale; Color: Translucent grayish-brown, beige, and tan; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Hexagonal (microcrystalline in chalcedony); Cleavage: None (conchoidal fracture).
- Hardness
- 6
- Color
- Translucent grayish-brown, beige, and tan
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Translucent grayish-brown, beige, and tan; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Hexagonal (microcrystalline in chalcedony); Cleavage: None (conchoidal fracture).
Formation & geological history
Formed via hydrothermal activity or secondary precipitation in volcanic, metamorphic, and sedimentary rocks, often within cavities, geodes, or veins.
Uses & applications
Used extensively in lapidary work, decorative carving, tumbled stones, wire-wrapped jewelry, and mineral collections.
Geological facts
Quartz and its chalcedony varieties are among the most abundant minerals on Earth. Its translucent brownish hues are typically created by natural irradiation or trace impurities.
Field identification & locations
Identified by its scratch resistance against steel (Mohs ~7), conchoidal fracture pattern, waxy to vitreous luster, and translucent warm-brown tone. Found worldwide in alluvial gravels, pegmatites, and volcanic beds.
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