Smoky quartz

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. Smoky quartz is dichroic in polarized light and will fade in color if heated to above 200-300 C or exposed to UV light. It may turn a pale yellow color resembling citrine; some heat-treated smoky quartz is sold commercially as citrine. 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.

Varieties

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

Cairngorm is a variety of smoky quartz found in the Cairngorm Mountains of Scotland. 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).

Uses

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

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

References

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

References

1. 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. (1990). "Handbook of Mineralogy". Mineralogical Society of America.
4. "Quartz". Hudson Institute of Mineralogy.
5. "Quartz Mineral Data".
6. (1985). "Manual of Mineralogy". Wiley.
7. "Smoky Quartz: A transparent brown gem & gem material".
8. "Smoky Quartz". Hudson Institute of Mineralogy.
9. "smoky quartz". Encyclopaedia Brittanica.
10. "Citrine". Hudson Institute of Mineralogy.
11. "Morion". Hudson Institute of Mineralogy.
12. ''New Oxford American Dictionary'' (2nd ed., 2005), p. 1102.
13. (12 June 2006). "The Nature of the Cairngorms: Diversity in a Changing Environment". The Stationery Office.
14. {{Cite EB1911
15. "The Gemstone Smoky Quartz".
16. 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.