Smoky quartz

General
Category| Tectosilicate minerals, quartz variety
Formula
(repeating unit)| SiO2
Strunz classification| 04.DA.05
Dana classification| 75.01.03.01
Crystal system| α-quartz: trigonal trapezohedral class 3 2
β-quartz: hexagonal 622[1]
Space group| Trigonal 32
Unit cell| a = 4.9133 Å, c = 5.4053 Å; Z=3
Identification
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[2]
Fracture| Conchoidal
Tenacity| Brittle
Mohs scale hardness| 7 – lower in impure varieties (defining mineral)
Vitreous – waxy to dull when massive|re|er}}| Vitreous – waxy to dull when massive
Streak| White
Diaphaneity| Transparent to nearly opaque
Specific gravity| 2.65; variable 2.59–2.63 in impure varieties
Optical properties| Uniaxial (+)
Refractive index| nω = 1.543–1.545
nε = 1.552–1.554
Birefringence| +0.009 (B-G interval)
Pleochroism| weak, from red-brown to yellow-brown
Melting point| 1670 °C (β tridymite) 1713 °C (β cristobalite)[1]
Solubility| Insoluble at STP; 1 ppmmass at 400 °C and 500 lb/in2 to 2600 ppmmass at 500 °C and 1500 lb/in2[1]
Other characteristics| lattice: hexagonal, Piezoelectric, may be triboluminescent, chiral (hence optically active if not racemic)
References| [3][4][5][6][7]

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.

## Contents

* 1 Properties
* 2 Varieties
* 3 Uses
* 4 See also
* 5 References
* 6 External links

## Properties

Smoky quartz ranges in color from brown or smoky gray to a nearly opaque black. The color of smoky quartz is produced when natural gamma radiation, emitted from the surrounding rock, activates color centers around aluminum impurities within the crystalline quartz.[8][7] Smoky quartz is dichroic in polarized light and will fade in color if heated to above 200–300 °C (392–572 °F) or exposed to UV light. It may turn a pale yellow color resembling citrine; some heat-treated smoky quartz is sold commercially as citrine.[9][10] Gamma irradiation can restore color to faded smoky quartz crystals. Smoky quartz crystals that grew in certain environments such as pegmatites and alpine fissures tend to be evenly colored, while crystals originating in other environments tend to exhibit color zoning or phantoms. In some crystals, the color may be darker near the edges.[7]

## Varieties

Morion is a very dark brown to black opaque variety of smoky quartz. Morion is also the German name for smoky quartz.[11] The name is from a misreading of mormorion in Pliny the Elder.[12]

Cairngorm is a variety of smoky quartz found in the Cairngorm Mountains of Scotland.[13] It usually has a smoky yellow-brown colour, though some specimens are greyish-brown. It is used in Scottish jewellery and as a decoration on kilt pins and the handles of sgianan-dubha (anglicised: sgian-dubhs or skean dhu).Cite error: Invalid `<ref>` tag; refs with no name must have content

## Uses

Smoky quartz is common and was not historically important, but in recent times it has become a popular gemstone, especially for jewelry.[14]

Sunglasses, in the form of flat panes of smoky quartz, were used in China in the 12th century.[15]

## See also

* List of minerals
* Amethyst

## References

1. ↑ 1.0 1.1 1.2 Deer, W. A., R. A. Howie and J. Zussman, An Introduction to the Rock Forming Minerals, Logman, 1966, pp. 340–355 ISBN 0-582-44210-9
2. ↑ Berry, R. W., et al. “Quartz Cleavage and Quick Clays.” Science, vol. 184, no. 4133, 12 Apr. 1974, pp. 183–184, https://doi.org/10.1126/science.184.4133.183. Accessed 19 May 2025.
3. ↑ "Quartz". Handbook of Mineralogy. III (Halides, Hydroxides, Oxides). Chantilly, VA, US: Mineralogical Society of America. ISBN 0962209724. http://rruff.geo.arizona.edu/doclib/hom/quartz.pdf.
4. ↑ "Quartz". Hudson Institute of Mineralogy. https://www.mindat.org/min-3337.html.
5. ↑ "Quartz Mineral Data". http://www.webmineral.com/data/Quartz.shtml.
6. ↑ Hurlbut, Cornelius S.; Klein, Cornelis (1985). Manual of Mineralogy (20 ed.). ISBN 0-471-80580-7. https://archive.org/details/manualofmineralo00klei.
7. ↑ 7.0 7.1 7.2 "Smoky Quartz". Hudson Institute of Mineralogy. http://www.mindat.org/show.php?id=3689.
8. ↑ "Smoky Quartz: A transparent brown gem & gem material". https://geology.com/gemstones/smoky-quartz/.
9. ↑ "smoky quartz". Encyclopaedia Brittanica. https://www.britannica.com/science/smoky-quartz.
10. ↑ "Citrine". Hudson Institute of Mineralogy. https://www.mindat.org/min-1054.html.
11. ↑ "Morion". Hudson Institute of Mineralogy. http://www.mindat.org/min-6270.html.
12. ↑ New Oxford American Dictionary (2nd ed., 2005), p. 1102.
13. ↑ Shaw, Philip; Thompson, Des B. A. (12 June 2006) (in en). The Nature of the Cairngorms: Diversity in a Changing Environment. The Stationery Office. p. 22. ISBN 978-0-11-497326-1. https://books.google.com/books?id=mVp6qGygeVgC&pg=PA22.
14. ↑ "The Gemstone Smoky Quartz". http://www.minerals.net/gemstone/smoky_quartz_gemstone.aspx.
15. ↑ Joseph Needham, Science & Civilisation in China (Cambridge, England: Cambridge University Press, 1962), volume IV, part 1, page 121. Needham states that dark glasses were worn by Chinese judges to hide their facial expressions during court proceedings.

* Holden, Edward (1925). "The Cause of Color in Smoky Quartz and Amethyst" in American Mineralogist, vol. 9, pp. 203–252

## External links

* Mineral Galleries - smoky quartz

* v
* t
* e

Silica minerals

Crystalline|

* Coesite
* Cristobalite
* Keatite
* Moganite
* Quartz
* Seifertite
* Stishovite
* Tridymite

Cryptocrystalline|

* Chalcedony
* Chert
* Flint
* Jasper

Amorphous|

* Fulgurite
* Lechatelierite
* Opal

Miscellaneous|

* Tiger's eye

Notable varieties|

| Chalcedony|

* Agate
* Carnelian
* Chrysoprase
* Heliotrope
* Onyx

|

Opal|

* Fiorite
* Geyserite

Quartz|

* Amethyst
* Ametrine
* Herkimer diamond
* Smoky quartz
* Shocked quartz
* Prasiolite

* v
* t
* e

Jewellery

Forms|

* Anklet
* Barrette
* Belt buckle
* Belly chain
* Bindi
* Bolo tie
* Bracelet
* Brooch
* Chatelaine
* Collar pin
* Crown
* Cufflink
* Earring
* Ferronnière
* Lapel pin
* Necklace
* Pectoral
* Pendant
* Ring
* Tiara
* Tie chain
* Tie clip
* Tie pin
* Toe ring
* Watch
* pocket
* strap

Making|

| People|

* Bench jeweler
* Clockmaker
* Goldsmith
* Silversmith
* Jewelry designer
* Lapidary
* Watchmaker

|

Processes|

* Carving
* Casting
* centrifugal
* lost-wax
* vacuum
* Enameling
* Engraving
* Filigree
* Kazaziye
* Metal clay
* Plating
* Polishing
* Repoussé and chasing
* Soldering
* Stonesetting
* Wire sculpture
* Wire wrapped jewelry

Tools|

* Draw plate
* File
* Hammer
* Mandrel
* Pliers

Materials|

| Precious metals|

* Gold
* Palladium
* Platinum
* Rhodium
* Silver

|

Precious metal alloys|

* Britannia silver
* Colored gold
* Crown gold
* Electrum
* Shakudō
* Shibuichi
* Sterling silver
* Argentium sterling silver
* Tumbaga

Base metals|

* Brass
* Bronze
* Copper
* Nickel silver (alpac(c)a)
* Mokume-gane
* Pewter
* Pinchbeck
* Stainless steel
* Titanium
* Tungsten

Mineral gemstones|

* Aventurine
* Agate
* Amazonite
* Amethyst
* Beryl
* Carnelian
* Chrysoberyl
* Chrysocolla
* Diamond
* Diopside
* Emerald
* Fluorite
* Garnet
* Howlite
* Jade
* Jasper
* Kyanite
* Labradorite
* Lapis lazuli
* Larimar
* Malachite
* Marcasite
* Moonstone
* Obsidian
* Onyx
* Opal
* Peridot
* Prasiolite
* Quartz
* Ruby
* Sapphire
* Sodalite
* Spinel
* Sunstone
* Tanzanite
* Tiger's eye
* Topaz
* Tourmaline
* Turquoise
* Variscite
* Zircon

Organic gemstones|

* Abalone
* Amber
* Ammolite
* Copal
* Coral
* Precious coral
* Black coral
* Ivory
* Jet
* Nacre
* Operculum
* Pearl
* Tortoiseshell

Other natural objects|

* Bezoar
* Bog-wood
* Ebonite (vulcanite)
* Gutta-percha
* Hair
* Shell jewelry
* Spondylus shell
* Toadstone

Terms|

* Carat (mass)
* Carat (purity)
* Finding
* Millesimal fineness
* Art jewelry

Related topics
Body piercing
Fashion
Gemology
Phaleristics
Metalworking
Wearable art

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