Smoky quartz

Short description: Mineral, quartz variety

Smoky quartz

General
Category| Silicate minerals
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 to grey, opaque
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} Indistinct
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 green-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| [2][3][4][5]

Smoky quartz is a brownish grey, translucent variety of quartz that ranges in clarity from almost complete transparency to an almost-opaque brownish-gray or black crystals.[6] The color of smoky quartz is produced when natural radiation, emitted from the surrounding rock, activates color centers around aluminum impurities within the crystalline quartz. [7]

## Contents

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

## Varieties

Morion is a very dark brown to black opaque variety. Morion is the German, Danish, Spanish and Polish synonym for smoky quartz.[8] The name is from a misreading of mormorion in Pliny the Elder.[9]

Cairngorm is a variety of smoky quartz found in the Cairngorm Mountains of Scotland.[10] 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).[11] The largest known cairngorm crystal is a 23.6 kg (52 lb) specimen kept at Braemar Castle.

## Uses

Smoky quartz is common and was not historically important, but in recent times it has become a popular gemstone, especially for jewelry.[12]

Sunglasses, in the form of flat panes of smoky quartz, were used in China in the 12th century.[13]

## See also

* List of minerals

## 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. ↑ "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.
3. ↑ Quartz. Mindat.org. Retrieved on 2013-03-07.
4. ↑ Quartz. Webmineral.com. Retrieved on 2013-03-07.
5. ↑ Hurlbut, Cornelius S.; Klein, Cornelis (1985). Manual of Mineralogy (20 ed.). ISBN 0-471-80580-7. https://archive.org/details/manualofmineralo00klei.
6. ↑ "Smoky Quartz: Smoky Quartz mineral information and data.". http://www.mindat.org/show.php?id=3689.
7. ↑ "Smoky Quartz: A transparent brown gem & gem material". https://geology.com/gemstones/smoky-quartz/.
8. ↑ http://www.mindat.org/min-6270.html Morion on Mindat
9. ↑ New Oxford American Dictionary (2nd ed., 2005), p. 1102.
10. ↑ 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.
11. ↑ Chisholm, Hugh, ed (1911). "Cairngorm". Encyclopædia Britannica. 4 (11th ed.). Cambridge University Press. p. 952.
12. ↑ "The Gemstone Smoky Quartz". http://www.minerals.net/gemstone/smoky_quartz_gemstone.aspx.
13. ↑ 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

0.00

(0 votes)

Original source: https://en.wikipedia.org/wiki/Smoky quartz. Read more

|

Retrieved from "https://handwiki.org/wiki/index.php?title=Chemistry:Smoky_quartz&oldid=2960905"
*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template