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Model-like, cognac-colored zircon crystal (size: 1.0 cm) on calcite from Gilgit, Gilgit-Baltistan region, Pakistan
General and classification
other names
  • Hyacinth
  • slang
  • Malacon
  • Alvit
  • Cyrtolite

as well as countless other names (see under "Varieties")

chemical formula Zr [SiO 4 ]
Mineral class
(and possibly department)
Silicates and germanates - island silicates (nesosilicates)
System no. to Strunz
and to Dana
9.AD.30 ( 8th edition : VIII / A.09)
Similar minerals Chrysoberyl , andradite (variety demantoid), rutile , monazite , cassiterite , xenotime (Y) , titanite
Crystallographic Data
Crystal system tetragonal
Crystal class ; symbol ditetragonal-dipyramidal; 4 / m  2 / m  2 / m
Space group I 4 1 / amd (No. 141)Template: room group / 141
Lattice parameters a  = 6.61  Å ; c  = 5.98 Å
Formula units Z  = 4
Frequent crystal faces Combination of prisms {100} and / or {110} with the dipyramid {101}
Twinning rarely knee-shaped twins with (112) as the twin plane
Physical Properties
Mohs hardness 7.5
Density (g / cm 3 ) measured: 4.6 to 4.7; calculated: 4.714
Cleavage very imperfect after {100}
Break ; Tenacity clamshell; brittle
colour usually brown and brownish red, more rarely yellow, green, blue and colorless
Line color White
transparency transparent to opaque (opaque)
shine Glass to diamond gloss, greasy gloss on broken surfaces; Greasy shine when metamict
radioactivity Pure formula, non-radioactive, with high U and Th contents one of the main carriers of radioactivity in rocks
Crystal optics
Refractive indices n ω  = 1.924 to 1.906
n ε  = 1.968 to 2.015
Birefringence δ = 0.044 to 0.055
Optical character uniaxial positive
Axis angle 2V = 10 ° (if abnormally biaxial)
Pleochroism mostly faint, distinct in strongly colored grains
Other properties
Chemical behavior Slightly soluble in hot, concentrated hydrofluoric acid
Special features Fluorescence , thermoluminescence , phosphorescence , cathodoluminescence , chatoyance (cat's eye effect)

Zircon is a mineral from the mineral class of " silicates and Germanates " with the chemical composition Zr [SiO 4 ] and thus chemically seen a zirconium - silicate which structurally to the island silicates counts. In some cases, high contents of hafnium , uranium , thorium , yttrium , cerium and other rare earth metals (Rare Earth Elements, REE) are very typical . Zircon is a complete solid solution series with its much rarer hafniumdominanten analogue hafnon . Reidit is a high pressure modification of zircon.

The mineral crystallizes in the tetragonal crystal system and mostly develops short prismatic crystals with a square cross-section and pyramidal crystal ends as well as crystals with a dipyramidal habit . The mostly ingrown, rarely grown crystals can reach a size of 30 cm. Zircon is also found in radial aggregates , irregular grains, massive and in the form of unrolled, strongly rounded crystals. In its pure form, zircon is colorless and transparent. However, due to multiple refraction due to lattice defects or polycrystalline formation, it can also appear white, whereby colorless to white zircons are rarely found. Usually, the mineral takes on a gray, brown to red-brown and, more rarely, yellow, green or blue color due to various foreign admixtures .

Specimens that show gem quality due to their size and purity are popular substitutes for diamonds due to their diamond-like sheen . Zirconium should not be confused with the synthetically produced zirconia (formula: ZrO 2 , zirconium (IV) oxide ), which is also used as a gemstone and imitation diamond.

Etymology and history

Red zircon from an unnamed site in Pakistan

The name zircon comes either from the Arabic zarqun for " vermilion " or from the Persian زرگون zargun for "gold-colored". These designations can be found changed in the name jargon , with which bright zircons have been named.

The name hyacinth (hyacinth), used since ancient times, originally referred to a blue or purple mineral. It comes from the Greek word Υάκινθος hyakinthos for "youth" - in Greek mythology, Hyakinthos was a flower that arose from the blood of the youth of the same name. Already in the year 300 BC the mineral of Theophrastus of Eresos was named after the Greek word λυγκύριον lyncurion as Lyncurion . A mineral that is probably identical to today's zircon is called by Pliny the Elder in his natural history ( Naturalis historia ) from around AD 77, Chrysolithos . By Georgius Agricola in 1546 as Hyacinthus and Barthelemy Faujas de Saint-Fond in 1772 as Hyacinthe called.

Jean-Baptiste Romé de L'Isle was the first to depict the characteristic crystal shape of the zircon with prism and pyramid and differentiated between elongated columnar and pseudorhombic dodecahedral varieties. Martin Heinrich Klaproth pointed out that Romé was the first to think of the Jargon de Ceylan "as a special type of stone". The mineral was first referred to as zircon (Silex Circonius) in 1783 by Abraham Gottlob Werner , whose student Christian August Siegfried Hoffmann included the zircon in the "Handbook of Mineralogy" he wrote after Werner's lectures.

"The name zircon is either of Zeilan origin, or from the French word jargon, with which the jewelers used to refer to all those uncolored gemstones which, when cut, deceive the eye by an apparent resemblance to the Demante, by corruption."

- Christian August Siegfried Hoffmann

Martin Heinrich Klaproth analyzed yellow-green and reddish zircons from Ceylon (today Sri Lanka ) in 1789 and discovered “a previously unknown, independent, simple earth”, which he named “zirconia” (Terra circonia) . Klaproth found the same soil in a hyacinth from Ceylon, whereby zircon on the one hand and hyacinth on the other hand turned out to be "two species or genera of a peculiar stone family"; the new earth could possibly also be called "hyacinth herd". It was only René-Just Haüy who combined hyacinth and zircon with precise determination of the crystal forms into a single mineral. The Swedish physician and chemist Jöns Jakob Berzelius isolated the chemical element zirconium for the first time .

A type locality (location of the material of the first description) for the zircon is not known, therefore there are no correspondingly defined mineral samples ( type material ).


Already in the outdated, but still in use 8th edition of the mineral classification according to Strunz , zircon belonged to the mineral class of "silicates and germanates" and there to the department of " island silicates (nesosilicates)", where it was named after the "zircon group" with the system No. VIII / A.09 and the other members Coffinit , Hafnon, Reidit, Thorit and Thorogummit .

The 9th edition of Strunz's mineral systematics , which has been in force since 2001 and is used by the International Mineralogical Association (IMA), also classifies zircon in the category of "island silicates (nesosilicates)". However, this is further subdivided according to the possible presence of further anions and the coordination of the cations , so that the mineral according to its composition can be found in the subsection of "Island silicates without further anions with cations in octahedral [6] and usually greater coordination", where it together with Coffinit, Hafnon, Stetindit , Thorit and Thorogummit the "Zircon group" with the system no. 9.AD.30 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns zircon to the class of "silicates and Germanates" and there in the department of "island silicate minerals ". Here he is the namesake of the " zircon group " with the system no. 51.05.02 and the other members Hafnon, Thorit, Coffinit, Thorogummit and Stetindit can be found within the subdivision of “Island silicates: SiO 4 groups only with cations in> [6] coordination”.


SEM image ( BSE mode ) of a zonal grown zircon

The formula of the pure zirconium with end link composition Zr [SiO 4 ] requires contents of 67.1 wt .-% (weight percent) ZrO 2 and 32.9 wt .-% SiO 2 . Natural zircons often contain a wide range of accompanying elements outside the formula and inclusions of various other minerals, including segregation , storage and zoned adhesions. The most important accompanying elements are hafnium, thorium, uranium, yttrium, cerium and other rare earth metals as well as phosphorus , niobium , tantalum , aluminum , iron and calcium . The isotype of zirconium (Zr [SiO 4 ]) and xenotime (Y) (Y [PO 4 ]) is the cause of the coupled (heterovalent) substitution of Zr 4+ and Si 4+ by Y 3+ and P 5+ . The greater part of the sometimes very high Y content is not due to a diadochronous incorporation of yttrium for zircon, but to zoned, sometimes even epitaxial adhesions with the discrete foreign mineral xenotime (compare the SEM picture opposite and under varieties ).

Hafnium was first detected in zircons from Norway by X-ray spectroscopy by the physicists Dirk Coster and George de Hevesy in Copenhagen in 1923. It also quickly became clear that hafnium is always contained in zirconium-containing minerals - and thus in all zirconia - because Hf 4+ ions have an ionic radius comparable to the lighter homologue Zr 4+ due to the lanthanide contraction and thus fit perfectly into the crystal structures of the zirconium -Connections fit. With its hafniumdominanten analogue hafnon (Hf [SiO 4 ]) zirconium thus forming a complete solid solution series. Contents of 45.30% by weight of hafnium dioxide (HfO 2 ) and of 27.69% by weight of zirconium dioxide (ZrO 2 ) characterize the center of the mixed crystal row with the formula (Zr 0.50 Hf 0.50 ) Σ = 1, 00 SiO 4 . Crystals with a hafnium dioxide content> 45.30% by weight are then hafnones; if the value is less than 45.30% by weight, it is zirconium. The HfO 2 content of the zirconia is normally about 1 to 1.5% by weight, the Hf / Zr ratio 0.02-0.04.

In extreme cases, zirconium can also contain up to 12% by weight thorium dioxide (ThO 2 ) or 1.5% by weight uranium (V, VI) oxide (U 3 O 8 ). A variety of zirconia containing yttrium was called ribeirite and contains 7.45% by weight of Y 2 O 3 (“ytter earth”). In a gray-green to gray-brown zirconium from Hayamadake, prefecture Fukushima, Japan, 10.14 wt .-% Y were 2 O 3 found.

The sometimes considerable contents of uranium and thorium make zircon the main carrier of radioactivity in rocks. However, pure formula zirconia is also weakly radioactive, since it consists of 2.8% of the isotope 96 Zr, which with its extremely long half-life of 24 · 10 18 years decays to 96 Mo with double beta decay.

Crystal structure

Unit cell of zircon
Structure of the zircon with island-like [SiO 4 ] 4+ tetrahedra and edge-linked ZrO 8 dodecahedra

Zircon crystallizes tetragonally in the space group I 4 1 / amd (space group no. 141) with the lattice parameters a  = 6.61  Å and c  = 5.98 Å as well as four formula units per unit cell . Template: room group / 141

The structure of the zirconium containing island-like [SiO 4 ] 4- - tetrahedron in a body-centered unit cell of Zr 4+ ions wherein each Zr 4+ ion of eight O 2- is surrounded ions. The [SiO 4 ] 4− tetrahedra are mirror-symmetrical and arranged along four-fold screw axes. The latter have opposite directions of rotation parallel [001] through the center of the four quarter cells. The basic structural element in the zirconium are zig-zag chains of alternating, edge-sharing ZrO 8 - dodecahedra parallel [100] obtained by common edges and corners with the [SiO 4 ] 4- are connected to a three-dimensional framework tetrahedra. Zircon is isotypic to Xenotime- (Y), Béhierite (Ta [BO 4 ]), Chernovite- (Y) , Hafnon, Thorite and Wakefieldite- (Y) as well as a number of artificial compounds, i. H. it crystallizes with the same structure as these minerals and phases.

In some zirconia, the lattice structure is partially destroyed ( metamictized ) by the action of high-energy radiogenic particles (from the radioactive decay of the elements uranium and thorium contained in zirconia ) - such crystals usually have darker, brown colors. Through metamictization, water can be stored in the crystal lattice. The result is a noticeable reduction in the refractive index , density and hardness. There is no longer any birefringence at all. In this respect, zircons are differentiated in terms of their stages

  • High zircons (normal, crystalline zircons),
  • Deep zircons (metamictic zircons),
  • intermediate zircons,

which are between the first two groups in terms of their properties. By heating to over 1000 ° C, the deep zirconia can recrystallize to form high zirconia.



Zirconia almost always forms all around formed, but ingrown and rarely grown, often square crystals in cross-section, the average size of which, e.g. B. in granitoid rocks, between 100 and 300 µm. Occasionally, however, they also reach sizes of several centimeters, especially in pegmatites or heavy mineral soaps . The largest known zircon in the world to date measured 10 cm × 10 cm × 30 cm, weighed over 7 kg and was found near Brudenell in the Canadian province of Ontario .

In most cases, zirconium crystals are terminated at both ends. Their length / width ratios, reflecting the speed of crystallization, vary between 1 and 5. In fact, needle-like crystals are often found in rapidly crystallized, porphyry , sub-volcanic intrusions as well as granites and gabbros intruding near the surface .

Zircons essentially come in three different basic types with the main surface shapes {100}, {110}, {101} and {301} (see also the corresponding graphics). These three basic morphological types of zircon include a pyramidal habit with {101} and / or {211}, a prismatic habit with {100} and / or {110} and an elongated habit with prismatic and pyramidal surface shapes. The pyramidal habit includes the typical dipyramidal crystals which show the pyramid {101} alone or with narrow surfaces of the prism II. Position {100}. The crystals with a prismatic habit are much more common. Here, in addition to the prisms that determine the costume position II {100} and / or I position {110}, the tetragonal pyramids II position {101} and {301}, the tetragonal pyramid I position {112} and the tetragonal dipyramid {211 }. Short prismatic crystals with {110} and {101}, which have a pseudorhombic dodecahedral habit (so-called hyacinth habit) and are reminiscent of corresponding garnet crystals ("garnets"), are very characteristic (compare crystal drawing no. 3).

When comparing with historical crystal drawings, it must be noted that the arrangement of the crystals in modern drawings is rotated by 45 ° compared to the previous morphological orientation. So the pyramid that was previously indexed as {111} is now set up as {101}.

In contrast to the shape- like minerals cassiterite and rutile , zirconia rarely forms knee-shaped twins with (112) as the twin plane. Such twins have been described from the "Meredeth Freeman Zircon Mine" in Henderson County in North Carolina , as well as cross-shaped twins according to (101) and gray-headed twins according to (111). However, as early as 1904, Georges Friedel questioned the regularity of the cross-shaped twins . Large twins according to (112), but not cross-shaped, but as knee twins, are mainly known from Brudenell Township, Renfrew County, Ontario in Canada.

Epitaxial growth of zirconium (green / blue crystal) with xenotime (Y) (violet crystal)

Zircon is also found in grape, kidney and radial-ray aggregates and irregular grains. Due to its resistance to weathering , zircon is found in loose sediments and soaps in the form of loose, unrolled crystals, in slag and xenolites linked to basaltic rocks , in skeletal and tree-shaped aggregates.

Adhesions with other minerals such as B. Xenotime (Y), including perfectly oriented (epitaxial) intergrowths (see the adjacent crystal drawing). Adhesions with baddeleyite are called "zircon favas" or "caldasite". Since thorite and zircon have completely analogous structures, epitaxial adhesions of zircon with thorite are also possible. These are known from Bassano Romano , Province of Viterbo , Latium , from the San Vito quarry near San Vito not far from Ercolano , Monte Somma , Somma Vesuvius complex, metropolitan city of Naples , Campania , both in Italy , as well as from the ejections of the Laacher- Lake volcanoes in the Vulkaneifel .

physical and chemical properties

In its pure form, zircon is colorless and water-clear-transparent. However, due to multiple refraction due to lattice construction defects or polycrystalline training, it can also be translucent white and, due to foreign admixtures, take on a brown and red-brown, and more rarely yellow, green or blue color. The line color of the zircon, however, is always white. The surfaces of the transparent to opaque crystals have a strong glass-like to diamond-like sheen on all surfaces , but a greasy sheen on fractured surfaces and in the metamorphosed state. Some zircons also show chatoyance (cat's eye effect ).

Zircon has a very imperfect cleavage after {100}, but due to its brittleness it breaks like quartz , whereby the fracture surfaces are formed like a shell. With a Mohs hardness of 7.5, zircon is one of the hard minerals and is thus between the reference minerals quartz (hardness 7) and topaz (hardness 8). The measured density for zirconium is 4.6 to 4.7 g / cm³, depending on the author, the calculated density is 4.714 g / cm³. During metamictization (isotropization) the density of the mineral drops to values ​​of 3.9 to 4.2 g / cm³ ("low density zircons").

At normal pressure , zircon is stable up to a temperature of 1676 ° C. In addition, it decomposes into tetragonal zirconium dioxide (ZrO 2 ) and silicon dioxide (SiO 2 ) in the modification β- cristobalite (high cristobalite) , i.e. it does not have a congruent melting point.

From 1689 ° C SiO 2 - rich melt (~ 95 mol% SiO 2 ) is formed, which becomes increasingly richer in ZrO 2 as the temperature rises .

In the thin section , zircon is colorless to pale brown and shows a distinct pleochroism in strongly colored grains . A pleochroism from ω = clove brown to ε = asparagus green was observed on brownish-pearl-gray grains, a pleochroism from ω = gray-violet-blue to ε = gray-olive-green on pale clove-brown grains, and a pleochroism from ω = pale blue to ε = pale yellow on yellowish-white grains. The mineral is characterized by high light refraction (strong relief with a dark border) and high birefringence (δ = 0.044 to 0.055) with vivid red, blue and green interference colors of the II and III. Order. Metamictic zircons can be abnormally biaxial and then show axis angles of 2V = 10 °, while their birefringence decreases to values ​​of δ = 0.000. Further characteristics are the often existing zonal structure and the pleochroic courtyards, which can best be recognized when the zircon appears as an inclusion in colored minerals such as biotite and tourmaline. In the zircon itself, inclusions of apatite , monazite , xenotime (Y), rutile, hematite , ilmenite , magnetite , biotite , cassiterite, quartz, tourmaline and glass have been observed, which always cause a certain turbidity (gray color).

The zirconium is infusible in front of the soldering tube , even in a stream of warm air. With oxygen it turns white without melting. A white enamel is only created on the surface with heated oxygen ; the latter also when the zircon begins to melt when heated in a stream of oxyhydrogen . Zircon is not noticeably attacked by phosphorus salt. If the powder is melted together with caustic potash - or with soda on a platinum wire - and then boiled with hydrochloric acid, turmeric paper is colored orange by the diluted acidic liquid (reaction to zirconium). If the hydrochloric acid solution is concentrated until crystallization and then boiled with saturated potassium sulfate solution, a white precipitate of zirconium (IV) oxide is formed. It is insoluble in acids . Zirconium is only attacked in the finest powder by concentrated sulfuric acid (H 2 SO 4 ); it is slightly soluble in hot, concentrated hydrofluoric acid (HF). Zircon can be broken down by melting with alkali carbonates and potassium disulfate and other bisulfates, but especially with potassium fluoride and hydrogen fluoride-potassium fluoride .

Glowing - depending on the treatment in the oxidation or reduction flame - sometimes creates a darker color, and sometimes the crystals are discolored. Some zircon crystals show during annealing thermal luminescence ; Particularly in the case of lighter, transparent crystals, “very mild warming” produces a bright to intensely green light, with the phosphorescence lasting two to three minutes. Zirconium can also have cathodoluminescence and yellow, orange-yellow to green-orange fluorescence in short-wave UV light (254 nm). This is caused by radiation-induced crystal defects and the incorporation of (UO 2 ) 2+ (uranyl ion) as an impurity, or Dy 3+ , Er 3+ , Nd 3+ , Yb 3+ . Lattice defects caused by radiation can heal when heated, sometimes sunlight is sufficient, which is accompanied by a loss of the color caused by this defect. As a result, the color changes - all that remains is the color due to stable defects such as foreign ions - or it disappears completely.

Modifications and varieties

Hafnium-rich, brown “Alvit” from the feldspar mine in Tangen, Kragerø, Telemark, Norway
Straw-yellow crystals of the zircon variety "Jargon" from the Poudrette Quarry, Mont Saint-Hilaire, Canada (field of view: 1.3 mm × 1.5 mm)

In the past, various zircons that were rich in rare earth metals (REE) were described under their own names. These include Alvit, Hagatalith, Naëgit, Nogizawalith, Oyamalith and Yamaguchilith. The mostly highly metamorphosed minerals come mainly from granites and granite pegmatites in Japan. Their REE 2 O 3 and P 2 O 5 contents can, for. B. in Nogizawalith, 26 wt .-% and 9.8 wt .-% achieve. It was shown decades ago that these zircon "varieties" are actually (zoned) adhesions of zircon and xenotime (Y), occasionally even in perfect epitaxial orientation. It is very likely that they originated from the action of hydrothermal solutions enriched in yttrium, phosphorus and rare earth metals on metamorphosed zirconia. In Alvit, the adhesions with xenotime (Y) crystals up to 0.1 mm in size are relatively coarse. In Hagatalith and Yamaguchilith, the xenotime domains are smaller and rarer, whereas in Oyamalith and Naëgite no discrete phase boundaries are discernible at all.

  • As Alvit a zircon Kragerø in Norway with up to 16% HfO was 2 and Th and REE named. This name was later used for metamictic, Hf-rich zircons made from granite pegmatites.
  • Anderbergit is a pseudododecahedral crystal-forming and altered zircon from Ytterby in Sweden named by Christian Wilhelm Blomstrand after the pharmacist and outstanding mineral expert CW Anderberg . This zircon variety was described by Adolf Erik Nordenskiöld . Anderbergite was found grown on black mica plates with fergusonite and xenotime and turned out to be a cyrtolite-like hydrous zirconium silicate with calcium and REE.
  • Auerbachite was named after the Russian scientist Dr. Auerbach named in Moscow. Hans Rudolf Hermann described the crystals ingrown in silica slate from the area around the village of Anatolia near "Hutor Masurenki" not far from Mariupol in the Ukraine.
  • As Azorit one in Sanidinit of was São Miguel in the Azores sitting zircon with extremely dipyramidalem habit called.
  • Caldasite is the name of a mixture of baddeleyite and zircon, originally known as the so-called zircon favas ("zircon beans") . These come from the Poços de Caldas massif , which is considered to be uranium-containing zirconium ore due to the average content of> 60% ZrO 2 and 0.3% U 3 O 8 .
  • Calyptolite (also caliptolite or kalyptolite ) is the name chosen by Charles Upham Shepard for a tiny crystal-forming zircon from the chrysoberyl locality Haddam in Connecticut, USA.
  • Cyrtolite (also Kyrtolite ) from the Greek κυρτός for "crooked" because of the curved pyramid surfaces is the name of William J. Knowlton for a zircon from the granite of Rockport in Massachusetts, USA.
  • Engelhardit are colorless to yellowish white, translucent and shiny diamond crystals up to 12 mm in size from the gold fields in Tomsk, showing the costume determining the form {101}.
  • When Hyacinth (also Jacinth (us) ) refers to still yellow and yellow to red-brown Zirkonvarietäten.
  • Jargon is a straw yellow to almost colorless variety of zirconia.
  • Malakon from the Greek μαλακός [ malakos ] for "soft" is the name given by Theodor Scheerer for an opaque and isotropic zircon which was first described from the island of Hidra (formerly Hitterø) in Norway .
  • Naëgite is a fully metamictized, Y-Th-U-rich variety of zircon from the pegmatite district of Naëgi, Japan. The variety Hagatalith containing Nb, Ta, Th and REE is similar , but in contrast to Naëgit it is richer in REE and poorer in zirconium.
  • Nogizawalith called Teikichi Kawai a mixture of xenotime and zircon.
  • Oerstedtite is a metamictic zircon from Arendal, Aust-Agder, Norway, mostly sitting on augite crystals . Johann Georg Forchhammer named the variety after Hans Christian Ørsted .
  • Ostranit was named by August Breithaupt after the Germanic spring goddess Ostra and is an altered zircon that probably comes from Arendal, Aust-Agder, Norway.
  • Polykrasilith, derived from the Greek πολύς for “much” and κρᾶσις for “mixture”, is the name chosen by Eduard Linnemann for zircons from North Carolina, USA due to the large number of spectroscopically proven elements in them (Sn, Pb, Cu, Bi, Zr, Al, Fe, Co, Mn, Zn, Mg, Ur, Er, Ca, Ka, Na and Li).
  • Ribeirite is an extremely yttrium-rich zircon from Macarani, Bahia, Brazil, which was named after the professor of mineralogy Joaquim Costa Ribeiro .
  • As Tachyaphaltit were by Nils Johan Berlin dark reddish brown crystals in named "granitic gneiss in precipitations in Kragero". The name was chosen after the Greek words ταχύ for "fast" and ἄφαλτος for "jumping down" because the crystals easily pop out when the rock is broken.
  • Yamaguchilith (also Yamazuchilith or Yamagulith ) is a REE-containing or REE- and P-rich zircon with 4-5% by weight P 2 O 5 from Yamaguchi near Kiso, Japan.

Education and Locations

Educational conditions

Zircon crystal with a clear pleochroic halo in the biotite of Punta Aiunu, Sardinia (field of view: 1 mm)

Zircon is one of the earliest mineral formations on earth and moon (see also age determination ). The oldest known zirconium crystals are up to 4.4 billion years old. As a microscopic, accessory mixture, it is present practically worldwide in various igneous rocks . As a primary crystallization product , it is a component of igneous rocks such as granites , syenites and alkali isenites and especially in their pegmatites , as well as in volcanics ( rhyolites and trachytes ). Large single crystals are mainly found in pegmatitic nepheline syenites. In metamorphic rocks (crystalline slates), zircon occurs as a secondary part in the form of crystals and grains inherited from the educts. Very large crystals and twins are known from Brudenell Township in Renfrew County, Ontario, Canada.

As a result of its resistance to chemical and mechanical weathering, zircon is also found in sedimentary rocks and in detritic form, which is understood to mean zircons exposed, transported and deposited from the rock formation by erosion . Zirconia enriched in this way can also be found in soaps , some of which reach dimensions relevant to deposits. In addition, zirconium is also on alpinotype fissures and volcanic Sanidin - outcasts to find.

Analyzes of the shape and crystal surface formation of zirconia allow conclusions to be drawn about the formation conditions and the further development of zirconia. As early as the 1950s, it was assumed that the morphology of zirconium as an early crystallizate reflects the physicochemical conditions at the time of its crystallization. These physicochemical factors include the chemical composition and viscosity of the magma as well as the surface tension of the crystals in relation to the melt and the rate of supercooling of the melt. From this, Jean-Pierre Pupin developed the theory that in granitic melts the relative size relationship of the two most common zirconia prisms - {100} and {110} - is controlled by the temperature and the formation of these two prisms consequently as a geothermometer for the formation temperature of the respective granitic rock can be used. On the other hand, it is disputed that the formation of the prismatic surfaces is controlled by the temperature of the magma and that the morphology of zirconium crystals can therefore be viewed as a geothermometer. Rather, the formation of the surface shapes {100} and {110} of the zirconium crystals should mainly be influenced by chemical conditions. An increased uranium and / or thorium content in a granitic melt affects or prevents, for example, the growth of {100} in favor of {110}, as a result of which crystals develop with morphologies dominated by the prism {110}.

Typical accompanying minerals of the zircon are - depending on the host rock (here in the sense of rock that contains usable minerals or precious stones) - the feldspars ( albite and microcline ), amphiboles , mica ( muscovite , biotite , phlogopite and vermiculite ) and quartz . The mineral is often found in soaps with other stable heavy minerals such as tourmaline, topaz , cassiterite, kyanite , sillimanite , corundum , garnet, spinel and occasionally gold . Soap deposits rich in zirconia are mined in India , the United States , Australia , Sri Lanka and South Africa .

So far (as of 2017), zirconia has been described as a frequent mineral formation in around 5100 sites. A type locality is not defined for the mineral. In view of the very large number of places where zircon was found, only a few localities, especially those that produce larger crystals, can be mentioned here.



The best-trained zircons in Germany come from ejections and xenolites of the Vulkaneifel , Rhineland-Palatinate . Red crystals with a length of up to 3 cm could be obtained from solidified lavas near Niedermendig . Volcanic sanidine ejections, e.g. B. from the Laacher See area, provide zircons that are fresh pink, but usually fade to colorless to gray-white tones. Zircons from the " Ettringer Bellerberg " (Caspar quarry) near Ettringen not far from Mayen show clear skeletal growth with a brush-like or tree-shaped formation . In the "Seufzergründel", 15 km southeast of Sebnitz , near Hinterhermsdorf in Saxon Switzerland , zirconium crystals up to 10 mm in size have been washed from soaps in a heavy mineral-bearing stream since at least 1546. Georgius Agricola writes:

"... colligitur etiam in Misenae rivo supra Hoensteinam arcem, distantem a stolpa ad V. M pass ..."

"... [he, the hyacinth] is also collected in a stream in the Meißner Land above Hohnstein Castle, about 5 miles from Stolpen ..."

Soap finds in the Göltzsch in the Saxon Vogtland and some of its tributaries led from 1994 to the qualitatively best and largest gemstone zircons in Europe. These come from a diatreme with a diameter of around 1 km near Ebersbrunn, southwest of Zwickau . Faceted, flawless zircons made from these soaps reach sizes of up to 1.7 cm and weigh up to 11  ct . The largest faceted zircon from this area was cut from a brown-red rough stone 2 cm × 1.6 cm in size and weighing 10.2 g. The largest "Göltzsch zircon" measured 4.4 cm × 3.6 cm × 3.8 cm and weighed 120 g - but it was not sanded. It is assumed that zirconia of this kind had edge lengths of up to 5 cm before the start of the fluvial transport.

In Switzerland , since 1997, zircons up to 9 cm in size, brown-pink to reddish-brown in nepheline pegmatites on the Gridone mountain massif above the Centovalli in the Ticino Alps , some of which are in coarse albite or apatite-containing biotite, and some in contact between albite and nepheline . The only zircon from an alpine rift in Switzerland is a 3.5 mm × 2 mm crystal that was recovered from the Rimpfischwäng near Zermatt in Valais. Zircon is also known from the granite of the Grimsel , Canton Bern and Canton Valais , as well as from the gneiss of Piz Blas and Piz Rondadura in Val Nalps near Sedrun in Canton Graubünden in crystals up to 1 mm in size.

Crystals up to 2.5 mm in size are known from Austria , especially from crevices in the amphibolite and biotite slate of the Totenkopf above the Stubach Valley in the Salzburger Land ; also from the "Aigner Alp" near Schellgaden in Murwinkel , Lungau , the "Dorfer Alpe" in the Dorferbachtal near Prägraten , Virgental , East Tyrol and from the "Prickler Halt", a ridge between Ladinger Spitz and Speikkogel on the Saualpe in Carinthia .

In Italy , zircons were found in the “Burgumer Alpe” in the Pfitscher Valley , South Tyrol and in the autonomous region of Trentino-South Tyrol with crystals up to 1 cm in size. The mineral was also found in “Le Prese”, Sondalo in Valtellina , Province of Sondrio in the Lombardy region , and from the quarry “Cave dell'Acqua” west of Figline di Prato near Monte Ferrato, Province of Prato , Tuscany . In the French Massif Central it occurred in hyacinth or brick-red, colorless or yellow crystals in the basalt tuff and sands of the Riou Pezzouliou near the village of Espaly near Le Puy-en-Velay , Haute-Loire , the Auvergne-Rhône-Alpes region as well in Trachyte - lava domes of the Puy-de-Dôme near Clermont-Ferrand , Puy-de-Dôme department , Auvergne-Rhône-Alpes region.

In Norway , zircon was found primarily in the “Store Kufjord” (actually the name of a fjord that cuts deep into the island) and other pegmatites on the island of Seiland , Finnmark, about 50 km north of Alta . The most zirconium-rich nepheline syenite pegmatite, 1.5 km long and up to 10 m thick, is located on the east bank of Store Kufjord and produced crystals up to 15 cm in size, which have a rounded appearance due to the formation of the steep pyramid {301}, which in some cases even determines costume (compare the crystal drawing No. 7). Further Norwegian sites for zircon are syenite pegmatites in the area of ​​the plutonic Larvik complex in the area of ​​the Langesundsfjord in the provinces of Vestfold and Telemark . Famous sites here are the island of Stokkøya, the “Tuften”, “Granit” and “Almenningen” quarries in Tvedalen, the “Saga I” quarry near Mørje, the Svenner Islands near Stavern and the Husefjell on Vesterøya near Sandefjord . Up to 10 cm large zirconium crystals come from the quarries Hàkestad and Stàlaker near Tjølling. Zircon, also in epitaxial intergrowths with xenotime (Y), comes from the feldspar quarry "Igletjødn" (Igletjern) near Hæstad farm and other granite pegmatites on the island of Hidra (Hitterø), Vest-Agder, south-southwest of Flekkefjord . The “Lindvikskollen” quarry, which was formerly built in the Lindvikskollen-Kalstadgangen pegmatite, and the “Tangen” feldspar mine, both near Kragerø not far from Fredrikstad , Telemark , are particularly known for the Alvit variety .

On the shores of Lake Ilmen in Ilmengebirge in Miass in the central Ural , Chelyabinsk Oblast , Russia , 1,826 crystals have been found with partly säuligem, partly pyramidal habit. The crystals, which are up to 17 cm long and 10 cm thick, come from nepheline syenites (miaskites), miaskitic pegmatites in granite gneiss, pegmatites in pyroxen syenites and granite pegmatites. One of the most famous sites is the "Bljumovskaja kop" chop. The Višnevye Mountains (Višnevogorsk), about 120 km north-northeast of Miass, belong, like the Ilmen Mountains, geologically to the Syserts-Ilmenogorsk anticlinory. They contain metasomatic albitites which are derived from alkaline rocks of miaskitic composition. These albitites, e.g. B. the one at the "Kurochkin Log" location, deliver zirconium crystals up to 10 cm in size. These albitites were mined as zirconium pyrochlore ore until the mid-1990s.

On the Kola peninsula in the Murmansk Oblast , two sites in particular have world-wide recognition : The “Peak Marchenko” of the Kukisvumchorr mountain in the Chibinen massif and the “Pegmatite No. 24” on the Vavnbed mountain (German: “Nackter Buttern ”) in the Lowosero massif . The former location yielded brown crystals up to 5 cm in size, from the latter, located in albite pegmatites, dipyramidal zirconium crystals (compare crystal drawing no. 1) up to 9 cm in size came.


In Africa , zircons are mainly found in the gemstone pegmatites and soaps in Madagascar , especially in the Fianarantsoa province . Well-known sites are the "Sakavalana Mine" (also type locality for Pezzottaite) near Ambatovita not far from Mandrosonoro, District Ambatofinandrahana , Region Amoron'i Mania , and the phlogopite deposit "Sakasoa" in District Iakora , Region Ihorombe , where "Sakasoa" also supplied zircon knee twins Has. Other well-known sites are in the Anosy region . These include Itrongay near Mahasoa East, Betroka district , and the Tranomaro community in the Amboasary district . Zircons also come from the pegmatites of Ampanobe in the pegmatite field of the same name near Ankazobe in the district of the same name, region Analamanga .

Another world-famous zirconium discovery site are the alkali pegmatites around Mount Malosa near Zomba on the plateau of the same name and in the district of the same name in Malawi . Geologically, they belong to the alkaline rock province of Chilwa and are famous for their large aegirine , feldspar and arfvedsonite crystals as well as rare beryllium minerals and minerals with rare earth metals .

Zircons have also been found at Imilchil in the High Atlas , Errachidia province , Drâa-Tafilalet region in Morocco since around 2000 . The sites of discovery include the Tizi-n'-Inouzane (Tizi-n-Ouazane) mountain pass, located approx. 18 km southeast of Imilchil, with almost centimeter-sized crystals on feldspar, and the mountain “Jebel Ewargizen” near Tirrhist. In addition to garnet, apatite and magnetite, zircon can also be found in pegmatites in episyenites.

A number of sites for zircon also exist in Mozambique . These include the Monte Salambidua near Tete in the province of the same name and the carbonatite from Luicuisse, 140 km northeast of Lichinga near the settlement of Navago in the province of Niassa . However, zircon is much more common in the pegmatites and tantalum deposits of the "Alto Ligonha district" sensu lato in the province of Zambezia . The sites include the Muiâne pegmatite (Emdal Mines) and the neighboring pegmatites Naipa, Maridge, Nanro, Nacuissupa and Nihire, the Isabela Mine and the Niesse Mine, the Muhano-Majamala-Cochiline pegmatite group, the Mocachaia-Alata-Intotcha- pegmatite group Nahora, the pegmatite group Namacotcha-Conco-Napire-Nassupe-Munhamola-Moneia, the pegmatite group Namivo-Tomeia-Nampoça and the Marropino pegmatite as well as the pegmatites of Boa Esperança, Namecuna, Namirrapo and Nuaparra. Crystals up to 6.5 cm × 3.5 cm × 3.5 cm have been described by Namecuna. In the localities mentioned, the zircon is found in the inner zones of the pegmatites accompanied by quartz, bismuthite and various representatives of the columbite series - in some pegmatites also in adhesions with xenotime (Y) or microlite . The yttrium, niobium-tantalum, thorium and uranium-rich zirconia variety Naëgite was observed in the Nuaparra pegmatite and accompanied there by quartz, bismuthite, thorite, rhabdophane and metatorbernite . The REE-, uranium- and thorium-rich variety Cyrtolite was found in Morrua, while altered, brownish zircons of the variety Malakon have been identified in the Ribaue area. Some zircons from the Alto Ligonha district, especially those from Namacotcha, have high HfO 2 contents of up to 32% by weight.


In Asia , zircon has been extracted from the gemstone soaps on Ceylon, today Sri Lanka , "in considerable quantities" since ancient times . The sites are mainly in a comparatively large area around the city of Ratnapura ( Sinhala : "City of Jewels") in the Ratnapura district in the Sabaragamuwa province . Also in the district of Ratnapura there are two sites that have delivered zirconium crystals up to 10 cm in size. These are the "Giant Crystal Quarry" near Embilipitiya and calcite veins in highly metamorphic biotite gneisses in the Katukubura Hills near Kolonne.

In Afghanistan , zircons are mainly known from the pegmatite field of Dara-i-Pech (Pech Valley) in the district of Chapa Dara , Kunar province . The Be-Nb-Ta-Li-rich pegmatites provide red, sharp-edged crystals of up to 8 cm in size and mostly dipyramidal habit. The Manogay (Managi) discovery area is also in the Pech Valley. The host rock of the zirconium crystals is not pegmatites, but Proterozoic marbles .

Numerous locations for excellently trained zircons are in Pakistan . These include the village of Harchu, district of Astore , 15 km north-north-west of Astore in the Astor Valley ; miarolithic granite pegmatites in the Stak Valley near Stak Nala, Rakaposhi Haramosh Mountains , Skardu District , Baltistan ; Alchuri in Shigar Valley, Skardu District, Baltistan; the Granitpegmatite of Chilas district Diamir , all in Gilgit-Baltistan (formerly Northern Areas), and 40 kilometers north-west of Peshawar located at Hameed Abad Kafoor Dheri Zagi Mountain (Shinwaro), Khyber Pakhtunkhwa (formerly North-West Frontier Province). The last-mentioned site is a 3 km × 5 km area with numerous alpinotype fissures.

Most zirconium crystals found in Myanmar are mostly single crystals - occasionally idiomorphic, more often more or less unrolled . These include the gem mining area "Thabeikkyin" east of the city of the same name (Thabeikkyin or Tha Pate Kyin Township) in the area of ​​the lower slopes of the Shan Plateau towards Mogok , as well as "Baw-lon-gyi West" (Bon-lon West) near the city Kyatpyin not far from Mogok, both in the Pyin U Lwin district in the Mandalay region of Myanmar. In the area of ​​the latter site, in addition to zircons, spinels, rubies and blue sapphires as well as painite are obtained from gravelly alluvions .

North America

There are many interesting sites for zirconia in the United States , including granite pegmatite in North Carolina . One of the most famous is undoubtedly the "Freeman Mine" or "Meredeth Freeman Zircon Mine" discovered by General Clingman in 1869 near Tuxedo in the "Zirconia Pegmatite District" within Henderson County . From the gray-brown zirconium crystals to be found here, Clingman exploited "1000 pounds in a few weeks" - even twins according to several laws. A pegmatite formerly mined on vermiculite in the "Tigerville Prospect", Greenville County , South Carolina , yielded zircons up to 3 cm in size. From an unnamed pegmatite near Mellen in Ashland County , Wisconsin , up to 20 cm long, fine-needle crystals ("crystals of zircon up to 7 1/4 inches long and 1/16 to 1/8 inch in diameter") have been described. Zircons, also known as "calyptolite" from the chrysoberyl locality of Haddam , Middlesex County , have also been found in granites near Haddam, Connecticut . According to George Frederick Kunz , zircons were found as "beautiful black crystals" near Franklin , Sussex County , New Jersey .

In the state of New York , various sites have long been known to have yielded larger crystals. At the exit of the "Two Ponds" in Orange County , crystals up to 2 cm in length were found together with scapolite , pyroxene and titanite ; at "Deer Hill" southeast of Canterbury dark brownish-red to black crystals up to 3 cm in length and at Amity, Town of Warwick , white, reddish and clove-brown and black crystals. At "Diana", Diana Township, Lewis County , crystals up to 4 cm long came together with titanite and scapolite; in St. Lawrence County apatite in granular limestones at "Robinson's" and Long's Mills (Harder Farm?) in the area of Hammond to 3 cm long crystals and in Rossie in Fine ( "Fred Scott Farm Pegmatites") and Pitcairn on .

Sharp-edged, shiny, brownish-red crystals up to 2 cm in size were recovered from the “Crystal King Zircon Mine” (“Ashton Location”) in the Wichita Mountains Wildlife Refuge near Indiahoma, Comanche County , Oklahoma . In the 1950s and 1960s, zircon was mined in the nearby "Hale Spring Pegmatite" located in the Cambrian Quanah granite. In Colorado from "Mount Cheyenne", or more correctly from the area "North Cheyenne Cañon - Helen Hunt Falls Area" near Colorado Springs , El Paso Co. , shiny reddish-brown, flesh-red or green, pyramidal zirconium crystals were found. From the “St. Peters Dome ”in the Cheyenne or St. Peters Dome District, El Paso County, there are sharp-edged, pyramidal, brown-pink zircon crystals up to 2 cm in size. Finally , prismatic zirconium crystals up to 5 cm in length are known from the "Pacoima Canyon Pegmatite Locality" (REE-U-Th) in the allanite pegmatite of Pacoima Canyon, San Gabriel Mountains , Los Angeles County , California .

From syenite pegmatites and lenses in the syenite gneisses of the "Kuehl Lake" locality located 23 km southwest of Eganville near Brudenell Township, Renfrew County , Ontario in Canada , very large, brownish to hyacinth-red, opaque crystals up to 30 cm in length and 10 cm in width came. which have been found together with apatite, titanite, hornblende and calcite. The site has been known since the early 1880s. The "Turner's Island Mine", which is also in Renfrew County, is located at the northern end of Turners Island in Lake Clear, approx. 5 km east of the western end of the lake and 12 km southwest of Eganville near Sebastopol Township. It has also been known since the 19th century and is one of the legendary sites in the world due to the giant crystals found here. From the corridors that pass through Hornblendegneise we know of a zirconium crystal one foot (approx. 30 cm) in length, an apatite weighing 700 pounds (approx. 315 kg), a titanite crystal that is also one foot long and titanite crystals up to 18 kg Weight. Several centimeters of twinned zirconium crystals come from here, as well as from the “Silver Crater Mine” (Basin Property), Faraday Township, Hastings County, famous for its “Betafit” crystals . At this site, which is probably a carbonatite intrusion in biotite amphibolite and syenitized gneiss, zircon is often associated with betafit. In the Regional County Municipality Témiscamingue in the region Abitibi-Témiscamingue in Quebec City of Lake Sheffield is open to the regionalmetamorph overprinted alkaline rock complex of Kipawa along the east side of the hill in mafic gneisses pegmatite lenses of coarse Eudialyt , feldspar, nepheline, agrellite and different representatives contains the Wöhlerite group as well as alkali amphibolites and non-agpaitic nepheline syenites. Here you can find beige-reddish to reddish-brown, centimeter-sized zirconium crystals, some of which are associated with magnesiocatophorite and / or mosandrite . Finally, in the “Poudrette Quarry” on Mont Saint-Hilaire , La Vallée-du-Richelieu Regional County , Montérégie , Québec, tiny but perfectly formed dipyramidal crystals of yellow color were found, which have been called “jargon”.

South America

In Brazil , brown to almost white, opaque zircon crystals up to several centimeters in size and megacrystals weighing more than 50 kg from nepheline syenites in the alkali rock complex of Peixe, state of Tocantins, occur. A frequently mentioned reference name is "Alminhas".

The alkali rock complex of Poços de Caldas in Minas Gerais provided, among other things, greenish dipyramidal crystals that sit in cavities in baddeleyite or form massive aggregates of "caldasite" - a mixture of zirconium and baddeleyite that only occurs here. Metamictic zircon in crystal groups up to 6 cm in size occurred in the pegmatite "Alto Assis Moraes" in Santa Luzia , Paraíba . From the “Naque” region in Minas Gerais, chestnut brown zirconium-hafnon mixed crystals several centimeters in length were reported.

Australia and Oceania

One of the sites with the world's largest zirconium crystals is "Mud Tank" at Alcoota Station, Strangways Range, Central Desert Region, Northern Territory , Australia . Mud Tank is a vermiculite-zirconium deposit in carbonatites, which is mined in open-cast mining. The Mud Tank collection area is 4 miles from Plenty Highway . The zirconium crystals found here can reach sizes of up to 2.5 cm, are honey to cinnamon brown, shiny wax and often have translucent areas.

In mostly unrolled form in soap deposits, zircon is mined in Cambodia , Thailand , Korea , Nigeria and Tanzania , in addition to sites in Myanmar, Sri Lanka, Australia, Brazil, Madagascar and Mozambique .

Zircon was also found in some mineral samples from the ocean floor in the Mid-Atlantic Ridge and Southwest Indian Ridge, and from deep drilling off the coast of New Jersey , as well as in some rock samples from the moon .


Zircon in biotite. Particles produced by radioactive alpha decay destroy the crystal lattice of the biotite and form pleochroic halos.

Age determination in geology

Since the development of radiometric age determination, zirconia has been of particular importance in geochronology , as it contains traces of the radioactive nuclides 235 U, 238 U and 232 Th (from 10 ppm up to 5% by weight). All of these isotopes decay into different lead isotopes via decay series . The age of crystallization of a zirconium can be determined by measuring the corresponding uranium-lead or thorium-lead ratios . Stable isotope ratios provide information about the environment in which the crystals were formed. Zircons retain this information because they are extremely resistant to geological influences such as weathering and even high-grade rock metamorphosis. Zircons from Mount Narryer and from the Jack Hills in the Narryer Gneiss Terran , Yilgarn Craton , Western Australia , which with an age of 4.404 billion years represent the oldest minerals found on Earth to date, point to a surprisingly early existence of continental crust and towards a liquid ocean. The Jack Hills are located south of the Murchison River on the border between the Shire of Murchison and the Shire of Meekatharra , about 800 km north of Perth . The oldest dated mineral in Europe is a 3.69 billion year old zircon crystal made of gneiss, which can be found in Øvre-Pasvik National Park in northern Norway, not far from the town of Kirkenes in the Pasvik Valley in the municipality of Sør-Varanger . Zircons in a lunar rock sample ( breccia 72215) were dated to 4.417 billion years and thus indicate a protracted solidification process of the lunar crust after the formation of the moon.

Provenance analysis in sediment petrology

Zircon plays an important role in the analysis of the heavy mineral spectrum of sedimentary rocks. By determining the crystal costume and crystal habit (this also includes the length / width ratio and the degree of rolling) of the zircons and determining their trace element content, the delivery areas of the sediments with their discrete rock types can be limited or even assigned and the processing, mechanical abrasion and sorting effects up to comprehensive transport processes ideally also be quantified for the deposition area of ​​the sediments.


Faceted zircons like these 5.5 mm or 13.5 ct stones from Vietnam exist in many shades
Blue zircon, 3.36 ct, Cambodia, heat treated
Honey-brown zircon of the hyacinth variety

Because of its high BG dispersion of 0.038 (in comparison: diamond: 0.044, zirconia : 0.066 and quartz : 0.013) larger specimens are valued gemstones. Colorless zircons are usually brilliant cut, colored stones are also step cut. Heat treatment can change the color of brown, red-brown or cloudy zircons. Colored zirconia become colorless or yellow to red-yellow when they are annealed under oxidizing conditions (850–900 ° C). When heat is applied under reducing conditions (900–1000 ° C), blue crystals form. It is difficult for laypeople to distinguish colorless zircon from diamond , as both minerals have a comparable brilliance and dispersion (“fire”). These properties led to the name Matara diamond . Such colorless zircons found in Sri Lanka were thought to be inferior diamonds in the 19th century. It is also possible for laypeople to confuse blue zircon with spinel . There are various trade names for colored zircons. As Ratanakiri derived from "Ratanakiri" ( Cambodian for "noble Steinberg"), blue zircon from the province be Preah Vihear in Cambodia , respectively. A variety of zirconia was also named with the term Starlit , which is given a blue hue by firing other zirconia at high temperatures. Kaduna zircons come from Nigeria and are characterized by their honey-yellow color. However, the colors obtained by firing are not always permanent - ultraviolet radiation and / or direct sunlight can cause changes in color.

One of the largest cut zircons known is kept at the Smithsonian Institution . It is brown in color and weighs 105.80 carats .


Zircon is the primary ore for both zirconium and hafnium. Zirconium is used as an alloy metal (ferrozirconium) and - in the form of the corrosion-resistant alloy Zircalloy (with small amounts of iron , chromium and tin ) - as a reactor material. Here it is used as a cladding material for fuel rods because of its small neutron capture cross- section. Zirconium-niobium alloys have superconducting properties, and most superalloys based on nickel and cobalt contain between 0.03 and 2.2% zirconium. Glasses made from zirconium fluorides have an extremely high infrared permeability and are therefore used in glass fiber technology. Zirconium glass is used to encase radioactive waste (e.g. plutonium) for final storage , and according to current research, the containers can withstand radiation for around 2000 years. Scientists led by Ian Farnan from the British Cambridge Nuclear Energy Center at the University of Cambridge have found out in experiments that the expected durability of zirconium glass against the plutonium isotope 239 Pu is only about 210 years.

The zirconia made from zirconium are artificially produced single crystals of zirconium (IV) oxide , which were stabilized in the cubic high-temperature phase and are often used as inexpensive diamond imitations for jewelry. Zirconia is difficult to distinguish visually from diamonds - the different thermal conductivity of both substances is used for this. While diamonds are particularly good at conducting heat, zirconia are particularly poor at conducting heat. Other relatively simple differences to diamonds that can be determined using non-destructive measuring methods are the different refraction of light ( refractive index zirconia 2.18, diamond 2.42), dispersion (zirconia 0.066, diamond 0.044) and density (zirconia 5.8 g / cm³, diamond 3 , 5 g / cm³). Stabilized zirconia is produced in various shapes and dimensions. Since the compound ZrO 2 has an extremely high melting point, slip-cast bricks made of polycrystalline zirconia or crucible material made of zirconia are used to manufacture mechanically resistant, acid-resistant and highly refractory materials. Such highly refractory oxide ceramics show only low heat conduction and thermal expansion.

In the chemical industry, zirconium is used in the manufacture of spinnerets , pipes, stirrers, valves and heat exchangers. Together with aluminum oxide or corundum , zircon is used as molding sand in foundries, in the glass industry and as an abrasive. Porous, ZrO 2 -based ceramics are excellent heat insulators - high-temperature glasses and metals with a high melting point can be melted in containers made of zirconia. Zirconia is also used in the manufacture of crucibles and abrasion-resistant materials such as dental implant abutments and dental crowns / bridges.

Zirconia applies eventually in the form of polycrystalline fibers for reinforcement in composite materials ( English composite material ) and in general for high-temperature insulation materials. The main areas of application for ZrO 2 fibers are high-temperature ovens and heat barriers in rockets, space shuttles and launch pads. High-temperature laboratory ovens insulated with such fibers can be heated up very quickly and then cooled down again very quickly. "Cemfil" glass fibers developed for the production of glass fiber reinforced cement contain a high proportion of zirconium and are therefore particularly resistant to alkalis. Although these fibers do not achieve the same reinforcement effects as asbestos, they are good substitutes for asbestos fibers because of their harmlessness.

Other zirconium compounds are used for glazes in the ceramic and glass industries. Such special ceramic products made with zircon include zircon porcelain, zircon steatite, zircon glazes and zircon enamels. The flame produced when zirconium is burned has a temperature of 4660 ° C and emits a pure white, sun-like light. Therefore, zirconium is used in flash lamps as well as in fireworks and tracer ammunition. Airbag inflators and pyrotechnic seat belt tensioners also contain zirconium.

"Zircon" in medicine

In popular scientific literature, zircon is sometimes incorrectly mentioned as a modern high-performance material in restorative medicine, especially dentistry. However, this usually does not mean the silicate zirconium, which is defined by its chemical formula ZrSiO 4 , but zirconium dioxide ZrO 2 with small additions of yttrium oxide to optimize the material properties. The silicate zircon, however, is not used in restorative medicine.


In the natural and healing writings of the medieval nun and polymath Hildegard von Bingen , the use of hyacinth as a healing stone is passed down. Depending on the implementation of the prescribed rules of use, it should be able to heal poor eyesight, cloudy eyes and eye pain, fever, heart problems and madness triggered by devilish spells. In addition, he can extinguish the “fire of the blood” ( libido ) in men and women through his inner warmth .

However, the hyacinth described by Hildegard von Bingen does not correspond to the yellow-red to brown zircon variety known today under this term, even if this is incorrectly claimed in many current esoteric publications. In the Greek word origin ὐάκινθος 'Hyacinthus' is the name for a blue shade and the flower genus of the same name . The historical hyacinth was therefore a blue stone

"It [the stone] has the name of a flower and is the color of the sky."

and thus an aquamarine , sapphire or turquoise .

Nevertheless, the zircon is also regarded by today's esotericists as an important healing stone, which is said to be able to eliminate varicose veins and water blisters on legs and feet and to heal testicular diseases. In addition, according to Uyldert (1983) it is assigned to Jupiter as a planetary stone in the hyacinth variety and, according to Richardson and Huett (1989), to Pluto as zircon . As an amulet stone, the zircon is assigned to the zodiac sign Virgo and as a monthly stone to December.


A red zircon plays the central role in Bert Saurbier's 2015 Eifel thriller of the same name . In a secret research center at Vogelsang Castle in the middle of the Eifel National Park , an international team of experts is working to reveal the secret of a fiery red zirconium crystal about two meters long. This is stuck in a billion year old Australian meteorite and creates a force field that causes objects in its vicinity to lose weight significantly.

See also


  • John M. Hanchar, Paul WO Hoskin (Ed.): Zircon (= Mineralogical Society of America [Ed.]: Reviews in Mineralogy and Geochemistry . Volume 53 ). 2003, ISBN 978-0-939950-65-2 , pp. 1-500 ( minsocam.org - Most comprehensive and timely work on zircon).
  • Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p. 468-471 .
  • Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 669–670 (first edition: 1891).
  • Helmut Schrätze , Karl-Ludwig Weiner : Mineralogy. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 681-683 .
  • Martin Okrusch, Siegfried Matthes: Mineralogy. An introduction to special mineralogy, petrology and geology . 7th fully revised and updated edition. Springer Verlag, Berlin a. a. 2005, ISBN 3-540-23812-3 , pp. 122-124 (first edition: 1983).
  • Gunnar Ries: Zircon as an accessory mineral . In: The opening . tape 52 , 2001, p. 381-383 .
  • Zircon . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 68 kB ; accessed on November 12, 2017]).
  • Gerhard Bayer, Hans-Georg Wiedemann: Zircon - from precious stone to mineral raw material . In: Chemistry in Our Time . tape 15 , no. 3 , 1981, p. 88-97 , doi : 10.1002 / ciuz.19810150305 .

Web links

Wiktionary: Zirkon  - explanations of meanings, word origins, synonyms, translations
Commons : Zirkon (Zircon)  - collection of images, videos and audio files

Individual evidence

  1. a b c d e Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  543 .
  2. a b Webmineral - Zircon (English)
  3. a b c d e f g h i j k l Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp.  669–670 (first edition: 1891).
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This article was added to the list of excellent articles on December 31, 2017 in this version .