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| formula = [[zirconium]] [[silicate]] ZrSiO<sub>4</sub>
| formula = [[zirconium]] [[silicate]] ZrSiO<sub>4</sub>
| molweight =
| molweight =
| color = brown, red, yellow, green, black, and colorless
| color = commonly brown brownish-red to black but can be red ([[niobium|Nb]]<sup>5+</sup>), yellow, green ([[uranium|U]]<sup>4+</sup>), and colorless
| habit = dipyramidal prismatic
| habit = dipyramidal prismatic
| system = [[Tetragonal]]; 4/m 2/m 2/m [[space group]] I41/amd
| system = [[Tetragonal]] 4/m 2/m 2/m
| symmetry = I41/amd
| Z = 4
| twinning =
| twinning =
| cleavage = indistinct, two directions
| cleavage = indistinct, two directions
| fracture = Subconchoidal to uneven—brittle
| fracture = Subconchoidal to uneven—brittle
| mohs = 7.5
| mohs = 7.5
| luster = Adamantine
| luster = subadamantine
| refractive = nω=1.967–2.015</br>nε=1.920–1.960
| refractive = nω=1.967–2.015</br>nε=1.920–1.960
| opticalprop =
| opticalprop =
| birefringence = δ=0.047–0.055
| birefringence = δ=0.047–0.055
| pleochroism =
| pleochroism =
| relief = high
| streak = White
| streak = White
| gravity = 4.6–4.7
| gravity = 4.6–4.7
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| solubility = Insoluble
| solubility = Insoluble
| diaphaneity =
| diaphaneity =
| other = [[Fluorescence|Fluorescent]] and [[radioactivity|radioactive]]
| other = [[Fluorescence|Fluorescent]] and [[radioactivity|radioactive]], may form [[pleochroic halos]]
}}
}}


'''Zircon''' (including '''hyacinth''' or yellow zircon) is a [[mineral]] belonging to the group of [[Silicate minerals|nesosilicates]]. Its chemical name is [[zirconium silicate]] and its corresponding chemical formula is [[Zirconium|Zr]][[Silicon|Si]][[Oxygen|O]]<sub>4</sub>. [[Hafnium]] is almost always present in quantities ranging from 1 to 4%. The crystal structure of zircon is [[tetragonal]] [[crystal system]]. The natural color of zircon varies between colorless, yellow-golden, red, brown, and green. Colorless specimens that show gem quality are a popular substitute for [[diamond]]; these specimens are also known as "Matura diamond". It is not to be confused with [[cubic zirconia]], a synthetic substance with a completely different chemical composition.
'''Zircon''' (including '''hyacinth''' or yellow zircon) is a [[mineral]] belonging to the group of [[Silicate minerals|nesosilicates]]. Its chemical name is [[zirconium silicate]] and its corresponding chemical formula is [[Zirconium|Zr]][[Silicon|Si]][[Oxygen|O]]<sub>4</sub>. A common empirical formula showing some of the range of substitution in zircon is (Zr<sub>1-y</sub>,[[Rare earth elements|REE]]<sub>y</sub>)(SiO<sub>4</sub>)<sub>1-x</sub>(OH)<sub>4x-y</sub>. Zircon forms in silicate melts with concentrated incompatible elements and accepts [[high field strength]] elements into it's structure. For example, [[Hafnium]] is almost always present in quantities ranging from 1 to 4%. The crystal structure of zircon is [[tetragonal]] [[crystal system]]. The natural color of zircon varies between colorless, yellow-golden, red, brown, and green. Colorless specimens that show gem quality are a popular substitute for [[diamond]]; these specimens are also known as "Matura diamond". It is not to be confused with [[cubic zirconia]], a synthetic substance with a completely different chemical composition.


The name either derives from the [[Arabic language|Arabic]] word ''zarqun'', meaning [[vermilion]], or from the [[Persian language|Persian]] ''zargun'', meaning golden-colored. These words are corrupted into "[[jargoon]]", a term applied to light-colored zircons. Yellow zircon is called ''"hyacinth"'', from the flower ''[[hyacinthus]]'', whose name is of Ancient Greek origin; in the Middle Ages all yellow stones of East Indian origin were called hyacinth, but today this term is restricted to the yellow zircons.
The name either derives from the [[Arabic language|Arabic]] word ''zarqun'', meaning [[vermilion]], or from the [[Persian language|Persian]] ''zargun'', meaning golden-colored. These words are corrupted into "[[jargoon]]", a term applied to light-colored zircons. Yellow zircon is called ''"hyacinth"'', from the flower ''[[hyacinthus]]'', whose name is of Ancient Greek origin; in the Middle Ages all yellow stones of East Indian origin were called hyacinth, but today this term is restricted to the yellow zircons.
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Zircon is a common accessory mineral that occurs worldwide. Noted occurrences include: [[Australia]]; [[Russia]] ([[Ural Mountains]]); Trentino, Monte Somma, and [[Vesuvius]], [[Italy]]; Arendal, [[Norway]]; [[Sri Lanka]]; [[India]]; [[Indonesia]] , [[Java]], [[Kalimantan]], [[Sulawesi]]; [[Thailand]]; [[Ratanakiri]], [[Cambodia]]; the Kimberley mines, [[Republic of South Africa]]; [[Madagascar]]; Renfrew County, [[Ontario]], and [[Grenville, Quebec]], [[Canada]]; and [[Litchfield, Maine]]; [[Chesterfield, Massachusetts]]; Essex, Orange, and St. Lawrence counties, [[New York]]; [[Henderson County, North Carolina]]; the [[Pikes Peak]] district of [[Colorado]]; and [[Llano County, Texas]] in the [[United States]]. Australia leads the world in zircon mining, producing 37% of the world total and accounting for 40% of world EDR (economic demonstrated resources) for the mineral. [[Thorite]] (ThSiO<sub>4</sub>) is an isostructural related mineral.
Zircon is a common accessory mineral that occurs worldwide. Noted occurrences include: [[Australia]]; [[Russia]] ([[Ural Mountains]]); Trentino, Monte Somma, and [[Vesuvius]], [[Italy]]; Arendal, [[Norway]]; [[Sri Lanka]]; [[India]]; [[Indonesia]] , [[Java]], [[Kalimantan]], [[Sulawesi]]; [[Thailand]]; [[Ratanakiri]], [[Cambodia]]; the Kimberley mines, [[Republic of South Africa]]; [[Madagascar]]; Renfrew County, [[Ontario]], and [[Grenville, Quebec]], [[Canada]]; and [[Litchfield, Maine]]; [[Chesterfield, Massachusetts]]; Essex, Orange, and St. Lawrence counties, [[New York]]; [[Henderson County, North Carolina]]; the [[Pikes Peak]] district of [[Colorado]]; and [[Llano County, Texas]] in the [[United States]]. Australia leads the world in zircon mining, producing 37% of the world total and accounting for 40% of world EDR (economic demonstrated resources) for the mineral. [[Thorite]] (ThSiO<sub>4</sub>) is an isostructural related mineral.


Zircon occurs in many different colors, including red, pink, brown, yellow, hazel, black, or colorless. The color of zircons can be changed by heat treatment. Depending on the amount of heat applied, colorless, blue, and golden-yellow zircons can be made. In geological settings, the development of pink, red, and purple zircon occurs after 100's of millions of years provided the crystal has sufficient trace elements to produce color centers. Color in this red or pink series is annealed in geological conditions above about 350°C.
Zircon occurs in many different colors, including red, pink, brown, yellow, hazel, black, or colorless. The color of zircons sometimes can be changed by heat treatment. Depending on the amount of heat applied, colorless, blue, and golden-yellow zircons can be made. In geological settings, the development of pink, red, and purple zircon occurs after 100's of millions of years provided the crystal has sufficient trace elements to produce color centers. Color in this red or pink series is annealed in geological conditions above about 350°C.


== Uses ==
== Uses ==
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Image:Zirkon 372.jpg|SEM image of zircon
Image:Zirkon 372.jpg|SEM image of zircon
</gallery>
</gallery>

==Similar Minerals==

[[Hafnon]] ([[hafnium|Hf]]SiO<sub>4</sub>), [[Xenotime]] ([[ytterbium|Y]][[phosphorus|P]]O<sub>4</sub>), Béhierite, Schiavinatoite ( ([[tantalum|Ta]],[[Niobium|Nb]])[[boron|B]]O<sub>4</sub> ), [[Thorite]], ([[thorium|Th]]SiO<sub>4</sub>), and [[Coffinite]] ([[Uranium|U]]SiO<sub>4</sub>) all share the same crystal structure (<sup>VIII</sup>X <sup>IV</sup>Y O<sub>4</sub>) as Zircon.


==See also==
==See also==

Revision as of 20:31, 16 September 2009

This article is about the mineral. For Zircon (disambiguation), see Zircon (disambiguation).
See also: cubic zirconium
Zircon
Zircon crystal from Tocantins, Brazil (2cm x 2cm)
General
CategoryMineral
Formula
(repeating unit)		zirconium silicate ZrSiO4
Crystal systemTetragonal 4/m 2/m 2/m
Space groupI41/amd
Identification
Colorcommonly brown brownish-red to black but can be red (Nb5+), yellow, green (U4+), and colorless
Crystal habitdipyramidal prismatic
Cleavageindistinct, two directions
FractureSubconchoidal to uneven—brittle
Mohs scale hardness7.5
Lustersubadamantine
StreakWhite
Specific gravity4.6–4.7
Refractive indexnω=1.967–2.015
nε=1.920–1.960
Birefringenceδ=0.047–0.055
FusibilityInfusible
SolubilityInsoluble
Other characteristicsFluorescent and radioactive, may form pleochroic halos

Zircon (including hyacinth or yellow zircon) is a mineral belonging to the group of nesosilicates. Its chemical name is zirconium silicate and its corresponding chemical formula is ZrSiO4. A common empirical formula showing some of the range of substitution in zircon is (Zr1-y,REEy)(SiO4)1-x(OH)4x-y. Zircon forms in silicate melts with concentrated incompatible elements and accepts high field strength elements into it's structure. For example, Hafnium is almost always present in quantities ranging from 1 to 4%. The crystal structure of zircon is tetragonal crystal system. The natural color of zircon varies between colorless, yellow-golden, red, brown, and green. Colorless specimens that show gem quality are a popular substitute for diamond; these specimens are also known as "Matura diamond". It is not to be confused with cubic zirconia, a synthetic substance with a completely different chemical composition.

The name either derives from the Arabic word zarqun, meaning vermilion, or from the Persian zargun, meaning golden-colored. These words are corrupted into "jargoon", a term applied to light-colored zircons. Yellow zircon is called "hyacinth", from the flower hyacinthus, whose name is of Ancient Greek origin; in the Middle Ages all yellow stones of East Indian origin were called hyacinth, but today this term is restricted to the yellow zircons.

Zircon is regarded as the traditional birthstone for December.

Properties

Optical microscope photograph; the length of the crystal is about 250 µm.

Zircon is a remarkable mineral, if only for its almost ubiquitous presence in the crust of Earth. It occurs in igneous rocks (as primary crystallization products), in metamorphic rocks and in sedimentary rocks (as detrital grains). Large zircon crystals are seldom abundant. Their average size, e.g. in granite rocks, is about 100–300 µm, but they can also grow to sizes of several centimeters (a few inches), especially in pegmatites.

Owing to their uranium and thorium content, some zircons may undergo metamictization. The processes, related to internal radiation damage, partially disrupt the crystal structure and partly explain the highly-variable properties of zircon. As zircon becomes more and more modified by internal radiation damage, the density decreases, the crystal structure is compromised, and the color changes.

Zircon is a common accessory mineral that occurs worldwide. Noted occurrences include: Australia; Russia (Ural Mountains); Trentino, Monte Somma, and Vesuvius, Italy; Arendal, Norway; Sri Lanka; India; Indonesia , Java, Kalimantan, Sulawesi; Thailand; Ratanakiri, Cambodia; the Kimberley mines, Republic of South Africa; Madagascar; Renfrew County, Ontario, and Grenville, Quebec, Canada; and Litchfield, Maine; Chesterfield, Massachusetts; Essex, Orange, and St. Lawrence counties, New York; Henderson County, North Carolina; the Pikes Peak district of Colorado; and Llano County, Texas in the United States. Australia leads the world in zircon mining, producing 37% of the world total and accounting for 40% of world EDR (economic demonstrated resources) for the mineral. Thorite (ThSiO4) is an isostructural related mineral.

Zircon occurs in many different colors, including red, pink, brown, yellow, hazel, black, or colorless. The color of zircons sometimes can be changed by heat treatment. Depending on the amount of heat applied, colorless, blue, and golden-yellow zircons can be made. In geological settings, the development of pink, red, and purple zircon occurs after 100's of millions of years provided the crystal has sufficient trace elements to produce color centers. Color in this red or pink series is annealed in geological conditions above about 350°C.

Uses

Sand-sized grains of zircon
  • Zircons are commercially mined for the metal zirconium, and are used for abrasive and insulating purposes.
  • It is the source of zirconium oxide(ZrO2), one of the most refractory materials known.
  • Crucibles of ZrO2 are used to fuse platinum at temperatures in excess of 1755 oC.
  • Zirconium metal is used in nuclear reactors due to its neutron absorption properties.
  • Large specimens are appreciated as gemstones, owing to their high refractive index. (Zircon has a refractive index of approximately 1.95; diamond's is approximately 2.4.)
  • Zircon is one of the key minerals used by geologists for geochronology .
  • Zircon is a part of the ZTR index to classify highly-weathered sediments.

Occurrence

World production trend of zirconium mineral concentrates

Zircon is a common accessory to trace mineral constituent of most granite and felsic igneous rocks. Due to its hardness, durability and chemical inertness, zircon persists in sedimentary deposits and is a common constituent of most sands. Zircon is rare within mafic rocks and very rare within ultramafic rocks aside from a group of ultrapotassic intrusive rocks such as kimberlites, carbonatites, and lamprophyre, where zircon can occasionally be found as a trace mineral owing to the unusual magma genesis of these rocks.

Zircon forms economic concentrations within heavy mineral sands ore deposits, within certain pegmatites, and within some rare alkaline volcanic rocks, for example the Toongi Trachyte, Dubbo, New South Wales Australia[1] in association with the zirconium-hafnium minerals eudialyte and armstrongite.

Zircons and radiometric dating

Zircon has played an important role during the evolution of radiometric dating. Zircons contain trace amounts of uranium and thorium (from 10 ppm up to 1 wt%) and can be dated using several modern analytical techniques. Because zircons can survive geologic processes like erosion, transport, even high-grade metamorphism, they contain a rich and varied record of geological processes. Currently, zircons are typically dated by uranium-lead (U-Pb), fission-track, and U+Th/He techniques.

Zircons from Jack Hills in the Narryer Gneiss Terrane, Yilgarn Craton, Western Australia, have yielded U-Pb ages up to 4.404 billion years,[2] interpreted to be the age of crystallization, making them the oldest minerals so far dated on Earth. In addition, the oxygen isotopic compositions of some of these zircons have been interpreted to indicate that more than 4.4 billion years ago there was already water on the surface of the Earth.[2][3] This interpretation is supported by additional trace element data[4][5], but is also the subject of debate[6][7].

Gallery

Similar Minerals

Hafnon (HfSiO4), Xenotime (YPO4), Béhierite, Schiavinatoite ( (Ta,Nb)BO4 ), Thorite, (ThSiO4), and Coffinite (USiO4) all share the same crystal structure (VIIIX IVY O4) as Zircon.

See also

References

Wikimedia Commons has media related to Zircon.

Footnotes

  1. ^ "Dubbo Zirconia Project Fact Sheet June 2007" (PDF). 06/2007. Retrieved 2007-09-10. {{cite web}}: |first= missing |last= (help); Check date values in: |date= (help)
  2. ^ a b c Wilde S.A., Valley J.W., Peck W.H. and Graham C.M. (2001). "Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4 Gyr ago" (PDF). Nature. 409: 175. doi:10.1038/35051550.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. ^ Mojzsis, S.J., Harrison, T.M., Pidgeon, R.T. (2001). "Oxygen-isotope evidence from ancient zircons for liquid water at the Earth's surface 4300 Myr ago". Nature. 409: 178–181. doi:10.1038/35051557.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. ^ Ushikubo, T., Kita, N.T., Cavosie, A.J., Wilde, S.A. Rudnick, R.L. and Valley, J.W. (2008). "Lithium in Jack Hills zircons: Evidence for extensive weathering of Earth's earliest crust". Earth and Planetary Science Letters. 272: 666-676. doi:10.1016/j.epsl.2008.05.032.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  5. ^ "Ancient mineral shows early Earth climate tough on continents". Physorg.com. June 13, 2008.
  6. ^ Nemchin, A.A., Pidgeon, R.T., Whitehouse, M.J. (2006). "Re-evaluation of the origin and evolution of >4.2 Ga zircons from the Jack Hills metasedimentary rocks". Earth and Planetary Science Letters. 244: 218–233. doi:10.1016/j.epsl.2006.01.054.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  7. ^ Cavosie, A.J., Valley, J.W., Wilde, S.A., E.I.M.F. (2005). "Magmatic δ18O in 4400–3900 Ma detrital zircons: a record of the alteration and recycling of crust in the Early Archean". Earth and Planetary Science Letters. 235: 663–681. doi:10.1016/j.epsl.2005.04.028.{{cite journal}}: CS1 maint: multiple names: authors list (link)

Notations

Further reading

  • John M. Hanchar & Paul W. O. Hoskin (eds.) (2003). "Zircon". Reviews in Mineralogy and Geochemistry, 53. ISBN 093995065-0 (Mineralogical Society of America monograph).
  • D. J. Cherniak and E. B. Watson (2000). "Pb diffusion in zircon". Chemical Geology. 172: 5–24. doi:10.1016/S0009-2541(00)00233-3.
  • A. N. Halliday (2001). "In the beginning…". Nature. 409: 144–145. doi:10.1038/35051685.
  • Hermann Köhler (1970). "Die Änderung der Zirkonmorphologie mit dem Differentiationsgrad eines Granits". Neues Jahrbuch Mineralogische Monatshefte. 9: 405–420.
  • K. Mezger and E. J. Krogstad (1997). "Interpretation of discordant U-Pb zircon ages: An evaluation". Journal of Metamorphic Geology. 15: 127–140. doi:10.1111/j.1525-1314.1997.00008.x.
  • J. P. Pupin (1980). "Zircon and Granite petrology". Contributions to Mineralogy and Petrology. 73: 207–220. doi:10.1007/BF00381441.
  • Gunnar Ries (2001). "Zirkon als akzessorisches Mineral". Aufschluss. 52: 381–383. doi:10.1007/BF00381441.
  • P. Tondar (1991). Zirkonmorphologie als Charakteristikum eines Gesteins. Dissertation an der Ludwig-Maximilians-Universität München, 87 pp.
  • G. Vavra (1990). "On the kinematics of zircon growth and its petrogenetic significance: a cathodoluminescence study". Contributions to Mineralogy and Petrology. 106: 90–99. doi:10.1007/BF00306410.
  • John W. Valley, William H. Peck, Elizabeth M. King, Simon A. Wilde (2002). "A Cool Early Earth". Geology. 30: 351–354. doi:10.1130/0091-7613(2002)030<0351:ACEE>2.0.CO;2. Retrieved 2005-04-11.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  • G. Vavra (1994). "Systematics of internal zircon morphology in major Variscan granitoid types". Contributions to Mineralogy and Petrology. 117: 331–344. doi:10.1007/BF00307269.
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