Zircon

Zircon, a captivating gemstone, derives its name from the Arabic word "zargun," meaning "golden-coloured." Composed primarily of zirconium silicate, zircon showcases a brilliant range of colours, including fiery reds, vibrant blues, and dazzling greens.

Geologically, zircon forms in a variety of environments, including igneous rocks and sedimentary deposits. Notable sources include Sri Lanka, Australia, and Brazil, each yielding distinctive colour varieties.

What distinguishes zircon is its remarkable dispersion, a quality that disperses light into a spectrum of vibrant flashes, earning it the nickname "earth's most sparkly gem." This dispersion, even higher than that of diamond, adds to its fiery brilliance when properly cut and polished.

One fascinating fact about zircon is its use in dating geological samples, as it contains trace amounts of radioactive isotopes that decay over time, allowing scientists to determine the age of the Earth's crust. Beyond its scientific importance, zircon's dazzling beauty continues to make it a cherished gemstone among collectors and connoisseurs worldwide.

Click on the terms in the table below to discover their meaning

Image of faceted blue Zircon — Faceted blue Zircon showing birefringence by Greg Polley (used under CC0 1.0 licence)

Image of faceted pink-brown Zircon — Faceted pink-brown Zircon by Ken Larsen (used under CC0 1.0 licence)

Image of faceted yellow-brown Zircon — Faceted yellow-brown Zircon by Ken Larsen (used under CC0 1.0 licence)

Click on the terms in the table below to discover their meaning

Name	Zircon
Category	Nesosilicate (Ziron group)
Chemical Formula	ZrSiO₄
Chemical Formula
IMA Symbol	Zrn
Crystal System	Tetragonal
Crystal Habit	Commonly as tabular to prismatic crystals, with square cross sections; also as irregular grains, massive
Twinning	Geniculated
Cleavage	Poor
Fracture	Conchoidal
Tenacity	Brittle
Hardness (Moh's Scale)	7.5
Specific Gravity	4.6 - 4.7
Diaphaneity	Transparent to opaque
Colour	Colourless, yellow, orange, red, pink, purple, blue, green, yellow-green, brownish-green, reddish brown, grey
Streak	White
Lustre	Adamantine to vitreous
Optical Class	Uniaxial (+)
Refractive index	nω = 1.925 - 1.961
	nϵ = 1.980 - 2.015

Birefringence	δ = 0.055
Dispersion	Rd = 0.039
Pleochroism	Weak


Clarity	Type II
Notable Varieties	Blue Zircon, Hyacinth (Jacinth) Zircon, Star Zircon (displays asterism)

References

Hudson Institute of Mineralogy. (2023). Zircon. Retrieved from Mindat.org: https://www.mindat.org/min-4421.html

Mineralogical Society of America. (2001). Zircon. In J. W. Anthony, R. A. Bideaux, K. W. Bladh, & M. C. Nichols (Eds.), Handbook of Mineralogy. Chantilly, VA 20151-1110, USA: Mineralogical Society of America. Retrieved from https://www.handbookofmineralogy.org/pdfs/zircon.pdf

Schumann, W. (2013). Gemstones of the World (17th ed.). (D. Shea, & N. Shea, Trans.) New York: Stirling Publishing Company.

About the Author

Daniel Gillespie is student of Web Development and the developer of Gemology 101. With a straightforward and informative approach, Daniel invites readers to explore the world of gemology, offering a valuable resource for both enthusiasts and those seeking knowledge about precious stones.