Key facts
- Category
- Tectosilicate minerals
- Group
- Quartz group
- Formula
- SiO 2
- Ima status
- Variety of quartz
- Strunz classification
- 04.DA.05
- Dana classification
- 75.01.03.01
- Crystal system
- α-quartz: trigonal trapezohedral class 3 2 , β-quartz: hexagonal 622
- Space group
- Trigonal 32
- Unit cell
- a = 4.9133 Å , c = 5.4053 Å; Z=3
- Colour
- Brown, gray, black
- Crystal habit
- 6-sided prism ending in 6-sided pyramid (typical), drusy, fine-grained to microcrystalline, massive
- Twinning
- Common Dauphine law, Brazil law and Japan law
- Cleavage
- {0110} none
- Fracture
- Conchoidal
- Tenacity
- Brittle
- Mohs scale hardness
- 7 – lower in impure varieties (defining mineral)
- Luster
- Vitreous – waxy to dull when massive
- Streak
- White
via Wikipedia infobox
Wikidata facts
- Subclass of
- quartz
- Image
- USDA Mineral Smokey Quartz 93v3949.jpg
Show 7 more facts
- described by source
- Mala hirnycha encyclopædia
- Commons category
- Smoky quartz
- Commons gallery
- Smoky quartz
- Mohs' hardness
- 7
- streak color
- white
- density
- 2.585
- chemical formula
- SiO₂
Sources (3)
via Wikidata · CC0
~2 min read
Encyclopedic overview
Smoky quartz is a brown to black, translucent variety of quartz. It ranges in clarity from almost complete transparency to almost-opaque black crystals. Smoky quartz is popular as a gemstone and as a collectible crystal.
Properties
Excerpted from Wikipedia’s “smoky quartz” article, available under the CC BY-SA 4.0 licence.