Zircon
Encyclopedia
Zircon (ˈzɜrkən; 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 Zr
SiO4
. 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 its 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, blue, and green. Colorless specimens that show gem quality are a popular substitute for diamond
; these specimens are also known as "Matura diamond".
The name either derives from the Syriac
word ܙܐܪܓܥܢܐ zargono, from the Arabic
word zarqun (زرقون), meaning vermilion
, or from the Persian
zargun (زرگون), meaning golden-colored. These words are corrupted into "jargoon
", a term applied to light-colored zircons. The English
word "Zircon" is derived from "Zirkon," which is the German
adaptation of these words. 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.
of Earth. It occurs in igneous rock
s (as primary crystallization products), in metamorphic rock
s and in sedimentary rock
s (as detrital grains). Large zircon crystals are rare. Their average size in granite
rocks is about 0.1–0.3 mm, but they can also grow to sizes of several centimeters, especially in pegmatite
s.
Because of their uranium
and thorium
content, some zircons might undergo metamictization
. Connected to internal radiation damage, these processes 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, occurring in Australia
; Barbados
; 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. Barbados produces 12% of the world total and 17% of world EDR accordingly.
Zircon occurs in many colors, including red, pink, brown, yellow, hazel, or black. It can also be colorless. The color of zircons can sometimes be changed by heat treatment. Depending on the amount of heat applied, colorless, blue, or golden-yellow zircons can be made. In geological settings, the development of pink, red, and purple zircon occurs after hundreds of millions of years, if the crystal has sufficient trace elements to produce color centers. Color in this red or pink series is annealed in geological conditions above the temperature about 350 °C.
, although this application is small, and all compounds of zirconium including zirconium oxide (ZrO2), one of the most refractory
materials known.
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 kimberlite
s, 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 pegmatite
s, and within some rare alkaline volcanic rocks, for example the Toongi Trachyte, Dubbo, New South Wales Australia in association with the zirconium-hafnium minerals eudialyte
and armstrongite.
. 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, 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. This interpretation is supported by additional trace element data, but is also the subject of debate.
(Hf
SiO4), Xenotime
(Y
P
O4), Béhierite, Schiavinatoite ((Ta
, Nb
)B
O4), Thorite
, (Th
SiO4), and Coffinite
(U
SiO4) all share the same crystal structure (VIIIX IVY O4) as Zircon.
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
belonging to the group of nesosilicates
Silicate minerals
The silicate minerals make up the largest and most important class of rock-forming minerals, constituting approximately 90 percent of the crust of the Earth. They are classified based on the structure of their silicate group...
. Its chemical name is zirconium silicate and its corresponding chemical formula is Zr
Zirconium
Zirconium is a chemical element with the symbol Zr and atomic number 40. The name of zirconium is taken from the mineral zircon. Its atomic mass is 91.224. It is a lustrous, grey-white, strong transition metal that resembles titanium...
SiO4
Silicate
A silicate is a compound containing a silicon bearing anion. The great majority of silicates are oxides, but hexafluorosilicate and other anions are also included. This article focuses mainly on the Si-O anions. Silicates comprise the majority of the earth's crust, as well as the other...
. 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
Incompatible element
An incompatible element is a term used in petrology and geochemistry to describe an element that is unsuitable in size and/or charge to the cation sites of the minerals, and is defined by the partition coefficient between rock-forming minerals and melt being much smaller than 1..During the...
elements into its structure. For example, hafnium
Hafnium
Hafnium is a chemical element with the symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869. Hafnium was the penultimate stable...
is almost always present in quantities ranging from 1 to 4%. The crystal structure of zircon is tetragonal crystal system
Crystal system
In crystallography, the terms crystal system, crystal family, and lattice system each refer to one of several classes of space groups, lattices, point groups, or crystals...
. The natural color of zircon varies between colorless, yellow-golden, red, brown, blue, and green. Colorless specimens that show gem quality are a popular substitute for diamond
Diamond
In mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions...
; these specimens are also known as "Matura diamond".
The name either derives from the Syriac
Syriac language
Syriac is a dialect of Middle Aramaic that was once spoken across much of the Fertile Crescent. Having first appeared as a script in the 1st century AD after being spoken as an unwritten language for five centuries, Classical Syriac became a major literary language throughout the Middle East from...
word ܙܐܪܓܥܢܐ zargono, from the Arabic
Arabic language
Arabic is a name applied to the descendants of the Classical Arabic language of the 6th century AD, used most prominently in the Quran, the Islamic Holy Book...
word zarqun (زرقون), meaning vermilion
Vermilion
Vermilion is an opaque orangish red pigment, similar to scarlet. As a naturally occurring mineral pigment, it is known as cinnabar, and was in use around the world before the Common Era began. Most naturally produced vermilion comes from cinnabar mined in China, and vermilion is nowadays commonly...
, or from the Persian
Persian language
Persian is an Iranian language within the Indo-Iranian branch of the Indo-European languages. It is primarily spoken in Iran, Afghanistan, Tajikistan and countries which historically came under Persian influence...
zargun (زرگون), meaning golden-colored. These words are corrupted into "jargoon
Jargoon
Jargoon or jargon is name applied by gemologists to those zircons which are fine enough to be cut as gemstones, but are not of the red color which characterizes the hyacinth or jacinth. The word is related to Arab zargun...
", a term applied to light-colored zircons. The English
English language
English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...
word "Zircon" is derived from "Zirkon," which is the German
German language
German is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....
adaptation of these words. 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.
Properties
Zircon is ubiquitous in the crustCrust (geology)
In geology, the crust is the outermost solid shell of a rocky planet or natural satellite, which is chemically distinct from the underlying mantle...
of Earth. It occurs in igneous rock
Igneous rock
Igneous rock is one of the three main rock types, the others being sedimentary and metamorphic rock. Igneous rock is formed through the cooling and solidification of magma or lava...
s (as primary crystallization products), in metamorphic rock
Metamorphic rock
Metamorphic rock is the transformation of an existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat and pressure causing profound physical and/or chemical change...
s and in sedimentary rock
Sedimentary rock
Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....
s (as detrital grains). Large zircon crystals are rare. Their average size in granite
Granitoid
A granitoid or granitic rock is a variety of coarse grained plutonic rock similar to granite which mineralogically are composed predominately of feldspar and quartz. Examples of granitoid rocks include granite, quartz monzonite, quartz diorite, syenite, granodiorite and trondhjemite. Many are...
rocks is about 0.1–0.3 mm, but they can also grow to sizes of several centimeters, especially in pegmatite
Pegmatite
A pegmatite is a very crystalline, intrusive igneous rock composed of interlocking crystals usually larger than 2.5 cm in size; such rocks are referred to as pegmatitic....
s.
Because of their uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
and thorium
Thorium
Thorium is a natural radioactive chemical element with the symbol Th and atomic number 90. It was discovered in 1828 and named after Thor, the Norse god of thunder....
content, some zircons might undergo metamictization
Metamictization
Metamictization is a natural process resulting in the gradual and ultimately complete destruction of a mineral's crystal structure, leaving the mineral amorphous...
. Connected to internal radiation damage, these processes 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, occurring in Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
; Barbados
Barbados
Barbados is an island country in the Lesser Antilles. It is in length and as much as in width, amounting to . It is situated in the western area of the North Atlantic and 100 kilometres east of the Windward Islands and the Caribbean Sea; therein, it is about east of the islands of Saint...
; Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
(Ural Mountains
Ural Mountains
The Ural Mountains , or simply the Urals, are a mountain range that runs approximately from north to south through western Russia, from the coast of the Arctic Ocean to the Ural River and northwestern Kazakhstan. Their eastern side is usually considered the natural boundary between Europe and Asia...
); Trentino, Monte Somma, and Vesuvius, Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
; Arendal, Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
; Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
; India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
; Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
, Java
Java
Java is an island of Indonesia. With a population of 135 million , it is the world's most populous island, and one of the most densely populated regions in the world. It is home to 60% of Indonesia's population. The Indonesian capital city, Jakarta, is in west Java...
, Kalimantan
Kalimantan
In English, the term Kalimantan refers to the Indonesian portion of the island of Borneo, while in Indonesian, the term "Kalimantan" refers to the whole island of Borneo....
, Sulawesi
Sulawesi
Sulawesi is one of the four larger Sunda Islands of Indonesia and is situated between Borneo and the Maluku Islands. In Indonesia, only Sumatra, Borneo, and Papua are larger in territory, and only Java and Sumatra have larger Indonesian populations.- Etymology :The Portuguese were the first to...
; Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
; Ratanakiri
Ratanakiri
Ratanakiri is a province in northeastern Cambodia that borders Laos to the north, Vietnam to the east, Mondulkiri Province to the south, and Stung Treng Province to the west. The province extends from the mountains of the Annamite Range in the north, across a hilly plateau between the Tonle San...
, Cambodia
Cambodia
Cambodia , officially known as the Kingdom of Cambodia, is a country located in the southern portion of the Indochina Peninsula in Southeast Asia...
; the Kimberley mines, Republic of South Africa; Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
; Renfrew County, Ontario
Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....
, and Grenville, Quebec
Grenville, Quebec
Grenville is a village and municipality in the Argenteuil Regional County Municipality, Quebec, Canada. It is located opposite Hawkesbury, Ontario, on the Ottawa River.-History:...
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
; and Litchfield, Maine
Litchfield, Maine
Litchfield is a town in Kennebec County, Maine, United States. The population was 3,110 at the 2000 census.-Geography:According to the United States Census Bureau, the town has a total area of , of which, of it is land and of it is water....
; Chesterfield, Massachusetts
Chesterfield, Massachusetts
Chesterfield is a rural hill town in Hampshire County, Massachusetts, United States, 28 miles southeast of Pittsfield and 108 miles west of Boston. The population was 1,201 at the 2000 census. It is part of the Springfield, Massachusetts Metropolitan Statistical Area.-History:Chesterfield was...
; Essex, Orange, and St. Lawrence counties, New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
; Henderson County, North Carolina
Henderson County, North Carolina
Henderson County is a county located in the U.S. state of North Carolina. It is part of the Asheville, North Carolina, Metropolitan Statistical Area. As of 2008, the population was 102,367. Its county seat is Hendersonville.- History :...
; the Pikes Peak
Pikes Peak
Pikes Peak is a mountain in the Front Range of the Rocky Mountains, west of Colorado Springs, Colorado, in El Paso County in the United States of America....
district of Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
; and Llano County, Texas
Llano County, Texas
Llano County is a county located on the Edwards Plateau in the U.S. state of Texas. In 2010, its population was 19, 301. Its county seat is Llano, and the county is named for the Llano River....
in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. 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
Thorite
Thorite, SiO4, is a rare nesosilicate of thorium that crystallizes in the tetragonal system and is isomorphous with zircon and hafnon. It is the most common mineral of thorium and is nearly always strongly radioactive. It was named in 1829 to reflect its thorium content...
(ThSiO4) is an isostructural
Isostructural
The term isostructural is used for chemical compounds that have similar chemical structures, and also with the meaning of isomorphous when used in relation to crystal structures...
related mineral. Barbados produces 12% of the world total and 17% of world EDR accordingly.
Zircon occurs in many colors, including red, pink, brown, yellow, hazel, or black. It can also be colorless. The color of zircons can sometimes be changed by heat treatment. Depending on the amount of heat applied, colorless, blue, or golden-yellow zircons can be made. In geological settings, the development of pink, red, and purple zircon occurs after hundreds of millions of years, if the crystal has sufficient trace elements to produce color centers. Color in this red or pink series is annealed in geological conditions above the temperature about 350 °C.
Applications
Zircon is mainly consumed as a opacifier in the decorative ceramics industry. It is also the principal precursor to metallic zirconiumZirconium
Zirconium is a chemical element with the symbol Zr and atomic number 40. The name of zirconium is taken from the mineral zircon. Its atomic mass is 91.224. It is a lustrous, grey-white, strong transition metal that resembles titanium...
, although this application is small, and all compounds of zirconium including zirconium oxide (ZrO2), one of the most refractory
Refractory
A refractory material is one that retains its strength at high temperatures. ASTM C71 defines refractories as "non-metallic materials having those chemical and physical properties that make them applicable for structures, or as components of systems, that are exposed to environments above...
materials known.
Occurrence
Granite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...
and felsic
Felsic
The word "felsic" is a term used in geology to refer to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium....
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 kimberlite
Kimberlite
Kimberlite is a type of potassic volcanic rock best known for sometimes containing diamonds. It is named after the town of Kimberley in South Africa, where the discovery of an diamond in 1871 spawned a diamond rush, eventually creating the Big Hole....
s, 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
Heavy mineral sands ore deposits
Heavy mineral sands are a class of ore deposit which is an important source of zirconium, titanium, thorium, tungsten, rare earth elements, the industrial minerals diamond, sapphire, garnet, and occasionally precious metals or gemstones....
, within certain pegmatite
Pegmatite
A pegmatite is a very crystalline, intrusive igneous rock composed of interlocking crystals usually larger than 2.5 cm in size; such rocks are referred to as pegmatitic....
s, and within some rare alkaline volcanic rocks, for example the Toongi Trachyte, Dubbo, New South Wales Australia in association with the zirconium-hafnium minerals eudialyte
Eudialyte
Eudialyte, whose name derives from the Greek phrase Εὖ διάλυτος eu dialytos, meaning "well decomposable", is a somewhat rare, red silicate mineral, which forms in alkaline igneous rocks, such as nepheline syenites...
and armstrongite.
Radiometric dating
Zircon has played an important role during the evolution of radiometric datingRadiometric dating
Radiometric dating is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates...
. 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
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
, transport, even high-grade metamorphism
Metamorphism
Metamorphism is the solid-state recrystallization of pre-existing rocks due to changes in physical and chemical conditions, primarily heat, pressure, and the introduction of chemically active fluids. Mineralogical, chemical and crystallographic changes can occur during this process...
, they contain a rich and varied record of geological processes. Currently, zircons are typically dated by uranium-lead
Uranium-lead dating
Uranium-lead is one of the oldest and most refined of the radiometric dating schemes, with a routine age range of about 1 million years to over 4.5 billion years, and with routine precisions in the 0.1-1 percent range...
(U-Pb), fission-track
Fission track dating
Fission track dating is a radiometric dating technique based on analyses of the damage trails, or tracks, left by fission fragments in certain uranium-bearing minerals and glasses...
, and U+Th/He techniques.
Zircons from Jack Hills
Jack Hills
The Jack Hills are a range of hills in Mid West Western Australia. They are best known as the source of the oldest material of terrestrial origin found to date: zircons that formed around 4.4 billion years ago...
in the Narryer Gneiss Terrane
Narryer Gneiss Terrane
The Narryer Gneiss Terrane is a geological complex in Western Australia that is composed of a tectonically interleaved and polydeformed mixture of granite, mafic intrusions and metasedimentary rocks in excess of 3.3 billion years old, with the majority of the Narryer Gneiss Terrane in excess of 3.6...
, Yilgarn Craton
Yilgarn craton
The Yilgarn Craton is a large craton which constitutes the bulk of the Western Australian land mass. It is bounded by a mixture of sedimentary basins and Proterozoic fold and thrust belts...
, Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
, have yielded U-Pb ages up to 4.404 billion years, interpreted to be the age of crystallization, making them the oldest minerals
Oldest rock
The oldest dated rocks on Earth, as an aggregate of minerals that have not been subsequently melted or disaggregated by erosion, are from the Archean Eon. Such rocks are exposed on the surface in very few places....
so far dated on Earth. In addition, the oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
isotopic
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
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. This interpretation is supported by additional trace element data, but is also the subject of debate.
Similar minerals
HafnonHafnon
Hafnon is a hafnium silicate mineral, chemical formula SiO4 or SiO4. In natural zircon ZrSiO4 part of the zirconium is replaced by the very similar hafnium and so natural zircon is never pure ZrSiO4...
(Hf
Hafnium
Hafnium is a chemical element with the symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869. Hafnium was the penultimate stable...
SiO4), Xenotime
Xenotime
Xenotime is a rare earth phosphate mineral, whose major component is yttrium orthophosphate . It forms a solid solution series with chernovite- and therefore may contain trace impurities of arsenic, as well as silicon dioxide and calcium...
(Y
Ytterbium
Ytterbium is a chemical element with the symbol Yb and atomic number 70. A soft silvery metallic element, ytterbium is a rare earth element of the lanthanide series and is found in the minerals gadolinite, monazite, and xenotime. The element is sometimes associated with yttrium or other related...
P
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
O4), Béhierite, Schiavinatoite ((Ta
Tantalum
Tantalum is a chemical element with the symbol Ta and atomic number 73. Previously known as tantalium, the name comes from Tantalus, a character in Greek mythology. Tantalum is a rare, hard, blue-gray, lustrous transition metal that is highly corrosion resistant. It is part of the refractory...
, Nb
Niobium
Niobium or columbium , is a chemical element with the symbol Nb and atomic number 41. It's a soft, grey, ductile transition metal, which is often found in the pyrochlore mineral, the main commercial source for niobium, and columbite...
)B
Boron
Boron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a metalloid. Because boron is not produced by stellar nucleosynthesis, it is a low-abundance element in both the solar system and the Earth's crust. However, boron is concentrated on Earth by the...
O4), Thorite
Thorite
Thorite, SiO4, is a rare nesosilicate of thorium that crystallizes in the tetragonal system and is isomorphous with zircon and hafnon. It is the most common mineral of thorium and is nearly always strongly radioactive. It was named in 1829 to reflect its thorium content...
, (Th
Thorium
Thorium is a natural radioactive chemical element with the symbol Th and atomic number 90. It was discovered in 1828 and named after Thor, the Norse god of thunder....
SiO4), and Coffinite
Coffinite
Coffinite is a uranium-bearing silicate mineral with formula: U1-x4x.It occurs as black incrustations, dark to pale-brown in thin section. It has a grayish black streak. It has a brittle to conchoidal fracture. The hardness of coffinite is between 5 and 6.It was first described in 1954 for an...
(U
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
SiO4) all share the same crystal structure (VIIIX IVY O4) as Zircon.
See also
- BaddeleyiteBaddeleyiteBaddeleyite is a rare zirconium oxide mineral , occurring in a variety of monoclinic prismatic crystal forms. It is transparent to translucent, has high indices of refraction, and ranges from colorless to yellow, green, and dark brown. Baddeleyite is a refractory mineral, with a melting point of...
, ZrO2 - Cool Early EarthCool Early EarthThe Cool Early Earth theory posits that the early planet Earth had a calm influx of bolides and a cool climate allowing fluid water, after the planetary accretion but before the occurrence of the Late Heavy Bombardment in the Hadean geological eon. The Cool Early Earth is believed to have been the...
- Heavy mineral sands ore depositsHeavy mineral sands ore depositsHeavy mineral sands are a class of ore deposit which is an important source of zirconium, titanium, thorium, tungsten, rare earth elements, the industrial minerals diamond, sapphire, garnet, and occasionally precious metals or gemstones....
- History of EarthHistory of EarthThe history of the Earth describes the most important events and fundamental stages in the development of the planet Earth from its formation 4.578 billion years ago to the present day. Nearly all branches of natural science have contributed to the understanding of the main events of the Earth's...
- IlmeniteIlmeniteIlmenite is a weakly magnetic titanium-iron oxide mineral which is iron-black or steel-gray. It is a crystalline iron titanium oxide . It crystallizes in the trigonal system, and it has the same crystal structure as corundum and hematite....
- List of minerals
- List of English words of Persian origin
- Oldest rockOldest rockThe oldest dated rocks on Earth, as an aggregate of minerals that have not been subsequently melted or disaggregated by erosion, are from the Archean Eon. Such rocks are exposed on the surface in very few places....
- Radiometric datingRadiometric datingRadiometric dating is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates...
External links
Further reading
- John M. Hanchar & Paul W. O. Hoskin (eds.) (2003). "Zircon". Reviews in Mineralogy and Geochemistry, 53. ISBN 0-939950-65-0 (Mineralogical Society of America monograph).