Carbonatite
   HOME

TheInfoList



OR:

Carbonatite () is a type of intrusive or
extrusive Extrusive rock refers to the mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the atmosphere to fall back as pyroclastics or tuff. In contr ...
igneous rock Igneous rock ( ), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial ...
defined by
mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...
ogic composition consisting of greater than 50%
carbonate mineral Carbonate minerals are those minerals containing the carbonate ion, . Carbonate divisions Anhydrous carbonates *Calcite group: trigonal **Calcite CaCO3 **Gaspéite (Ni,Mg,Fe2+)CO3 **Magnesite MgCO3 **Otavite CdCO3 **Rhodochrosite MnCO3 **Sider ...
s. Carbonatites may be confused with
marble Marble is a metamorphic rock consisting of carbonate minerals (most commonly calcite (CaCO3) or Dolomite (mineral), dolomite (CaMg(CO3)2) that have recrystallized under the influence of heat and pressure. It has a crystalline texture, and is ty ...
and may require geochemical verification. Carbonatites usually occur as small plugs within zoned alkalic intrusive complexes, or as dikes, sills,
breccia Breccia ( , ; ) is a rock composed of large angular broken fragments of minerals or Rock (geology), rocks cementation (geology), cemented together by a fine-grained matrix (geology), matrix. The word has its origins in the Italian language ...
s, and
veins Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and fetal c ...
. They are almost exclusively associated with continental
rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben ...
-related tectonic settings. It seems that there has been a steady increase in the carbonatitic
igneous Igneous rock ( ), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial ...
activity through the Earth's history, from the
Archean The Archean ( , also spelled Archaean or Archæan), in older sources sometimes called the Archaeozoic, is the second of the four geologic eons of Earth's history of Earth, history, preceded by the Hadean Eon and followed by the Proterozoic and t ...
eon to the present. Nearly all carbonatite occurrences are intrusives or subvolcanic intrusives. This is because carbonatite
lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...
flows, being composed largely of soluble carbonates, are easily weathered and are therefore unlikely to be preserved in the geologic record. Carbonatite eruptions as lava may therefore not be as uncommon as thought, but they have been poorly preserved throughout the
Earth's history The natural history of Earth concerns the development of planet Earth from its formation to the present day. Nearly all branches of natural science have contributed to understanding of the main events of Earth's past, characterized by consta ...
. Carbonatite liquid compositions are significantly more alkaline than what is preserved in the fossil carbonatite rock record as composition of the melt inclusions shows. Only one carbonatite
volcano A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most oft ...
is known to have erupted in historical time, the active Ol Doinyo Lengai volcano in
Tanzania Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...
. It erupts with the coolest lava in the world, at . The lava is natrocarbonatite dominated by
nyerereite Nyerereite is a very rare sodium calcium carbonate mineral with formula Na2 Ca( C O3)2. It forms colorless, platey pseudohexagonal orthorhombic crystals that are typically twinned. It has a specific gravity of 2.54 and indices of refraction of ...
and
gregoryite Gregoryite is an anhydrous carbonate mineral that is rich in potassium and sodium with the chemical formula . It is one of the two main ingredients of natrocarbonatite, found naturally in the lava of Ol Doinyo Lengai volcano of Arusha Region, Ta ...
.


Genesis

The magmatic origin of carbonatite was argued in detail by Swedish geologist Harry von Eckermann in 1948 based on his study of
Alnö Complex The Alnö Complex or Alnö Alkaline Complex is a group of carbonatite and Alkaline rocks, alkaline igneous rocks in Alnö in the eastern coast of central Sweden that intruded the basement (geology), basement in Ediacaran, Late Ediacaran times. The A ...
. It was however the 1960 eruption of Ol Doinyo Lengai in Tanzania that led to geological investigations that finally confirmed the view that carbonatite is derived from
magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also ...
. Carbonatites are ''rare'', ''peculiar'' igneous rocks formed by unusual processes and from unusual source rocks. Three models of their formation exist: # direct generation by very low-degree partial melts in the mantle and melt differentiation, # liquid immiscibility between a carbonate melt and a
silicate A silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is also used ...
melt, # peculiar, extreme crystal fractionation. Evidence for each process exists, but the key is that these are unusual phenomena. Historically, carbonatites were thought to form by melting of
limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
or
marble Marble is a metamorphic rock consisting of carbonate minerals (most commonly calcite (CaCO3) or Dolomite (mineral), dolomite (CaMg(CO3)2) that have recrystallized under the influence of heat and pressure. It has a crystalline texture, and is ty ...
by intrusion of
magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also ...
, but geochemical and mineralogical data discount this. For example, the carbon isotopic composition of carbonatites is mantle-like and not like sedimentary limestone. The age of carbonatites ranges from Archean to present: the oldest carbonatite, Tupertalik in Greenland, is 3007 Ma old, while Ol Doinyo Lengai volcano in Tanzania is presently active.


Mineralogy

Primary mineralogy is highly variable, but may include natrolite,
sodalite Sodalite ( ) is a tectosilicate mineral with the formula , with royal blue varieties widely used as an ornamental gemstone. Although massive sodalite samples are opaque, crystals are usually transparent to translucent. Sodalite is a member of th ...
,
apatite Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of Hydroxide, OH−, Fluoride, F− and Chloride, Cl− ion, respectively, in the crystal. The formula of the admixture of ...
,
magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula . It is one of the iron oxide, oxides of iron, and is ferrimagnetism, ferrimagnetic; it is attracted to a magnet and can be magnetization, magnetized to become a ...
,
baryte Baryte, barite or barytes ( or ) is a mineral consisting of barium sulfate (Ba S O4). Baryte is generally white or colorless, and is the main source of the element barium. The ''baryte group'' consists of baryte, celestine (strontium sulfate), ...
,
fluorite Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon. The Mohs scal ...
, ancylite group minerals, and other rare minerals not found in more common igneous rocks. Recognition of carbonatites may be difficult, especially as their mineralogy and texture may not differ much from
marble Marble is a metamorphic rock consisting of carbonate minerals (most commonly calcite (CaCO3) or Dolomite (mineral), dolomite (CaMg(CO3)2) that have recrystallized under the influence of heat and pressure. It has a crystalline texture, and is ty ...
except the presence of igneous minerals. They may also be sources of
mica Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into fragile elastic plates. This characteristic is described as ''perfect basal cleavage''. Mica is co ...
or
vermiculite Vermiculite is a hydrous phyllosilicate mineral which undergoes significant expansion when heated. Exfoliation occurs when the mineral is heated sufficiently; commercial furnaces can routinely produce this effect. Vermiculite forms by the weathe ...
. Carbonatites are classed as calcitic sovite (coarse textured) and alvikite (finer textured) varieties or
facies In geology, a facies ( , ; same pronunciation and spelling in the plural) is a body of rock with distinctive characteristics. The characteristics can be any observable attribute of rocks (such as their overall appearance, composition, or con ...
. The two are also distinguished by minor and
trace element __NOTOC__ A trace element is a chemical element of a minute quantity, a trace amount, especially used in referring to a micronutrient, but is also used to refer to minor elements in the composition of a rock, or other chemical substance. In nutr ...
composition.Peter Kresten
''Carbonatite nomenclature''
International Journal of Earth Sciences, Volume 72, Number 1 / February, 1983.
The terms ''rauhaugite'' and ''beforsite'' refer to dolomite- and
ankerite Ankerite, also known as '' brown spar''礦物學名詞: (俄英中对照試用本) Mineralogical Terminology (Russian-English-Chinese version). — Beijing: 中國科学院. 編譯出版委員会 Compilation and Publication Committee of Chinese A ...
-rich occurrences respectively. The alkali-carbonatites are termed ''lengaite''. Examples with 50–70% carbonate minerals are termed ''silico-carbonatites''. Additionally, carbonatites may be either enriched in
magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula . It is one of the iron oxide, oxides of iron, and is ferrimagnetism, ferrimagnetic; it is attracted to a magnet and can be magnetization, magnetized to become a ...
and
apatite Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of Hydroxide, OH−, Fluoride, F− and Chloride, Cl− ion, respectively, in the crystal. The formula of the admixture of ...
or
rare-earth element The rare-earth elements (REE), also called the rare-earth metals or rare earths, and sometimes the lanthanides or lanthanoids (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), are a set o ...
s,
fluorine Fluorine is a chemical element; it has Chemical symbol, symbol F and atomic number 9. It is the lightest halogen and exists at Standard temperature and pressure, standard conditions as pale yellow Diatomic molecule, diatomic gas. Fluorine is extre ...
and
barium Barium is a chemical element; it has symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element. Th ...
. '' Natrocarbonatite'' is made up largely of two minerals,
nyerereite Nyerereite is a very rare sodium calcium carbonate mineral with formula Na2 Ca( C O3)2. It forms colorless, platey pseudohexagonal orthorhombic crystals that are typically twinned. It has a specific gravity of 2.54 and indices of refraction of ...
(named after
Julius Nyerere Julius Kambarage Nyerere (; 13 April 1922 – 14 October 1999) was a Tanzanian politician, anti-colonial activist, and political theorist. He governed Tanganyika (1961–1964), Tanganyika as prime minister from 1961 to 1962 and then as presid ...
, the first president of independent
Tanzania Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...
) and
gregoryite Gregoryite is an anhydrous carbonate mineral that is rich in potassium and sodium with the chemical formula . It is one of the two main ingredients of natrocarbonatite, found naturally in the lava of Ol Doinyo Lengai volcano of Arusha Region, Ta ...
(named after
John Walter Gregory John Walter Gregory, , (27 January 1864 – 2 June 1932) was a British geologist and explorer, known principally for his work on glacial geology and on the geography and geology of Australia and East Africa. The Gregory Rift in the Great Rif ...
, one of the first geologists to study the
East African Rift The East African Rift (EAR) or East African Rift System (EARS) is an active continental rift zone in East Africa. The EAR began developing around the onset of the Miocene, 22–25 million years ago. It was formerly considered to be part of a l ...
and author of the book ''The Great Rift Valley''). These minerals are both
carbonate A carbonate is a salt of carbonic acid, (), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word "carbonate" may also refer to a carbonate ester, an organic compound containing the carbonate group ...
s in which
sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...
and
potassium Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...
are present in significant quantities. Both are
anhydrous A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achie ...
, and when they come into contact with the moisture in the atmosphere, they begin to react extremely quickly. The black or dark brown lava and ash erupted begins to turn white within a few hours, then grey after a few days, then brown after a few weeks.


Geochemistry

Carbonatites are unusual igneous rocks composed predominantly of
carbonate mineral Carbonate minerals are those minerals containing the carbonate ion, . Carbonate divisions Anhydrous carbonates *Calcite group: trigonal **Calcite CaCO3 **Gaspéite (Ni,Mg,Fe2+)CO3 **Magnesite MgCO3 **Otavite CdCO3 **Rhodochrosite MnCO3 **Sider ...
s. Most carbonatites tend to include some silicate mineral fraction; by definition an igneous rock containing >50% carbonate minerals is classified as a carbonatite. Silicate minerals associated with such compositions are
pyroxene The pyroxenes (commonly abbreviated Px) are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents ions of calcium (Ca), sodium (Na), iron ( ...
,
olivine The mineral olivine () is a magnesium iron Silicate minerals, silicate with the chemical formula . It is a type of Nesosilicates, nesosilicate or orthosilicate. The primary component of the Earth's upper mantle (Earth), upper mantle, it is a com ...
, and silica- undersaturated minerals such as
nepheline Nepheline, also called nephelite (), is a rock-forming mineral in the feldspathoid groupa silica-undersaturated aluminosilicate, Na3 K Al4 Si4 O16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatit ...
and other
feldspathoid The feldspathoids are a group of tectosilicate minerals which resemble feldspar Feldspar ( ; sometimes spelled felspar) is a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, pota ...
s. Geochemically, carbonatites are dominated by incompatible elements (Ba, Cs, Rb) and depletions in compatible elements (Hf, Zr, Ti). This together with their silica-undersaturated composition supports inferences that carbonatites are formed by low degrees of
partial melting Partial melting is the phenomenon that occurs when a rock is subjected to temperatures high enough to cause certain minerals to melt, but not all of them. Partial melting is an important part of the formation of all igneous rocks and some metamorp ...
. A specific type of
hydrothermal alteration Metasomatism (from the Greek μετά ''metá'' "change" and σῶμα ''sôma'' "body") is the chemical alteration of a Rock (geology), rock by hydrothermal and other fluids. It is traditionally defined as metamorphism which involves a change in t ...
termed ''fenitization'' is typically associated with carbonatite intrusions. This alteration assemblage produces a unique rock mineralogy termed a '' fenite'' after its type locality, the Fen Complex in
Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...
. The alteration consists of
metasomatic Metasomatism (from the Greek μετά ''metá'' "change" and σῶμα ''sôma'' "body") is the chemical alteration of a rock by hydrothermal and other fluids. It is traditionally defined as metamorphism which involves a change in the chemical com ...
halos consisting of sodium rich
silicates A silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is also used for an ...
arfvedsonite Arfvedsonite () or ''soda hornblende'' (partiellement obsolète) is a sodium amphibole mineral with composition: aNa2] Fe2+)4Fe3+(OH)2, Si8O22]. It crystallizes in the monoclinic prismatic crystal system and typically occurs as greenish black t ...
, barkevikite and glaucophane along with
phosphates Phosphates are the naturally occurring form of the element phosphorus. In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphor ...
,
hematite Hematite (), also spelled as haematite, is a common iron oxide compound with the formula, Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of . ...
and other iron and titanium oxides.Guilbert, John M. and Charles F. Park, Jr., 1986, ''The Geology of Ore Deposits'', Freeman, pp. 188 and 352–361


Occurrence

Overall, 527 carbonatite localities are known on Earth, and they are found on all continents and also on oceanic islands. Most of the carbonatites are shallow intrusive bodies of calcite-rich igneous rocks in form of volcanic necks, dykes, and cone-sheets. These generally occur in association with larger intrusions of alkali-rich silicate igneous rocks. The extrusive carbonatites are particularly rare, only 49 are known, and they appear to be restricted to a few continental rift zones, such as the Rhine valley and the East African rift system. Associated igneous rocks typically include ijolite, melteigite, teschenite,
lamprophyre Lamprophyres () are uncommon, small-volume ultrapotassic igneous rocks primarily occurring as dikes, lopoliths, laccoliths, stocks, and small intrusions. They are alkaline silica- undersaturated mafic or ultramafic rocks with high magnesium o ...
s,
phonolite Phonolite is an uncommon shallow intrusive or extrusive rock, of intermediate chemical composition between felsic and mafic, with texture ranging from aphanitic (fine-grained) to porphyritic (mixed fine- and coarse-grained). Phonolite is a var ...
, foyaite,
shonkinite Shonkinite is an intrusive igneous rock found in few places in the world. It is unique in having low silica, feldspathoid minerals, and large blocky crystals of black augite. It makes up much of the hard dark grey rock comprising certain mountains ...
, silica undersaturated foid-bearing
pyroxenite Pyroxenite is an ultramafic igneous rock consisting essentially of minerals of the pyroxene group, such as augite, diopside, hypersthene, bronzite or enstatite. Pyroxenites are classified into clinopyroxenites, orthopyroxenites, and the w ...
( essexite), and
nepheline syenite Nepheline syenite is a holocrystalline Intrusion, plutonic rock that consists largely of nepheline and alkali feldspar. The rocks are mostly pale colored, grey or pink, and in general appearance they are not unlike granites, but dark green varie ...
. Carbonatites are typically associated with undersaturated (low
silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f ...
) igneous rocks that are either alkali (Na2O and K2O), ferric iron (Fe2O3) and
zirconium Zirconium is a chemical element; it has Symbol (chemistry), symbol Zr and atomic number 40. First identified in 1789, isolated in impure form in 1824, and manufactured at scale by 1925, pure zirconium is a lustrous transition metal with a greyis ...
-rich agpaitic rocks or alkali-poor, FeO-CaO-MgO-rich and zirconium-poor miaskitic rocks. The Mount Weld carbonatite is unassociated with a belt or suite of alkaline igneous rocks, although calc-alkaline magmas are known in the region. The genesis of this Archaean carbonatite remains contentious as it is the sole example of an Archaean carbonatite in Australia.


Intrusive morphology

Carbonatite is known to form in association with concentrically zoned complexes of alkaline-igneous rocks, the typical example of this being Phalaborwa, South Africa. Carbonatites in the form of sills,
lopolith A lopolith is a large igneous intrusion which is lenticular in shape with a depressed central region. Lopoliths are generally concordant with the intruded strata with dike or funnel-shaped feeder bodies below the body. The term was first defined ...
s and rare dikes are reported in the Guyana Shield. The Mud Tank and Mount Weld carbonatites take the form of multi-stage cylindrical intrusive bodies with several distinct phases of carbonatite intrusion. Smaller carbonatite sills and dikes are present in other
Proterozoic The Proterozoic ( ) is the third of the four geologic eons of Earth's history, spanning the time interval from 2500 to 538.8 Mya, and is the longest eon of Earth's geologic time scale. It is preceded by the Archean and followed by the Phanerozo ...
mobile belts in Australia, typically as dikes and discontinuous pods.


Known examples

Dozens of carbonatites are known including: * the Bearpaw Mountains, Montana; * the Oka and
Saint-Honoré, Quebec Saint-Honoré () is a city in Quebec, Canada. It is the seat of Le Fjord-du-Saguenay Regional County Municipality and its most populous municipality. Demographics In the 2021 Canadian census, 2021 census conducted by Statistics Canada, Sain ...
; * Gem Park and Iron Hill, Colorado; * Magnet Cove igneous complex,
Arkansas Arkansas ( ) is a landlocked state in the West South Central region of the Southern United States. It borders Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, Texas to the southwest, and Oklahoma ...
; * Mountain Pass, California; * the Palabora Complex near
Phalaborwa Phalaborwa (translated to English as ''better than the south; phala'' means ''better than and borwa'' means ''south'') is a town in the Mopani District Municipality, Limpopo province, South Africa. Name The place was called "Phalaborwa" by the S ...
,
South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...
; * Jacupiranga,
Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...
; * Ayopaya, Bolivia; * Cerro Impacto,
Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...
; * Kovdor and Vischnevogorsk,
Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...
; * Amba Dongar and Newania from
India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
; * Maz, Argentina; * the Mud Tank and Mount Weld, Australia; * the Fen Complex, Norway; * part of the basal complex of
Fuerteventura Fuerteventura () is one of the Canary Islands, in the Atlantic Ocean, geographically part of Macaronesia, and politically part of Spain. It is located away from the coast of North Africa. The island was declared a biosphere reserve by UNESCO i ...
,
Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...
; * the Avon Volcanic District, Missouri; * the Elk Creek Carbonatite, Nebraska, USA. In 2017, the discovery of a new carbonatite deposit was confirmed north-west of
Prince George, British Columbia Prince George is a city in British Columbia, Canada, situated at the confluence of the Fraser River, Fraser and Nechako River, Nechako rivers. The city itself has a population of 76,708; the metro census agglomeration has a population of 89,490 ...
, in a region termed the "Rocky Mountain Rare Metal Belt". The volcano Ol Doinyo Lengai, in the
East African Rift The East African Rift (EAR) or East African Rift System (EARS) is an active continental rift zone in East Africa. The EAR began developing around the onset of the Miocene, 22–25 million years ago. It was formerly considered to be part of a l ...
is the world's only active carbonatite volcano. Other older carbonatite volcanoes are located in the same region, including
Mount Homa Mount Homa is a mountain and presumed extinct complex volcano located in western Kenya. It forms a broad peninsula on the southern shore of Winam Gulf, an extension of Lake Victoria. This peninsula defines Homa Bay and the mountaintop is about n ...
.


Economic importance

Carbonatites may contain economic or anomalous concentrations of
rare-earth element The rare-earth elements (REE), also called the rare-earth metals or rare earths, and sometimes the lanthanides or lanthanoids (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), are a set o ...
s (REEs),
phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...
,
niobium Niobium is a chemical element; it has chemical symbol, symbol Nb (formerly columbium, Cb) and atomic number 41. It is a light grey, crystalline, and Ductility, ductile transition metal. Pure niobium has a Mohs scale of mineral hardness, Mohs h ...
tantalum Tantalum is a chemical element; it has Symbol (chemistry), symbol Ta and atomic number 73. It is named after Tantalus, a figure in Greek mythology. Tantalum is a very hard, ductility, ductile, lustre (mineralogy), lustrous, blue-gray transition ...
,
uranium Uranium is a chemical element; it has chemical symbol, symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Ura ...
,
thorium Thorium is a chemical element; it has symbol Th and atomic number 90. Thorium is a weakly radioactive light silver metal which tarnishes olive grey when it is exposed to air, forming thorium dioxide; it is moderately soft, malleable, and ha ...
,
copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...
,
iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...
,
titanium Titanium is a chemical element; it has symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in ...
,
vanadium Vanadium is a chemical element; it has Symbol (chemistry), symbol V and atomic number 23. It is a hard, silvery-grey, malleable transition metal. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an ...
,
barium Barium is a chemical element; it has symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element. Th ...
,
fluorine Fluorine is a chemical element; it has Chemical symbol, symbol F and atomic number 9. It is the lightest halogen and exists at Standard temperature and pressure, standard conditions as pale yellow Diatomic molecule, diatomic gas. Fluorine is extre ...
,
zirconium Zirconium is a chemical element; it has Symbol (chemistry), symbol Zr and atomic number 40. First identified in 1789, isolated in impure form in 1824, and manufactured at scale by 1925, pure zirconium is a lustrous transition metal with a greyis ...
, and other rare or incompatible elements.
Apatite Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of Hydroxide, OH−, Fluoride, F− and Chloride, Cl− ion, respectively, in the crystal. The formula of the admixture of ...
,
barite Baryte, barite or barytes ( or ) is a mineral consisting of barium sulfate (Ba S O4). Baryte is generally white or colorless, and is the main source of the element barium. The ''baryte group'' consists of baryte, celestine (strontium sulfate), ...
and
vermiculite Vermiculite is a hydrous phyllosilicate mineral which undergoes significant expansion when heated. Exfoliation occurs when the mineral is heated sufficiently; commercial furnaces can routinely produce this effect. Vermiculite forms by the weathe ...
are among the industrially important minerals associated with some carbonatites. Trace elements are extremely enriched in carbonatites, and they have the highest concentration of lanthanides of any known rock type. The largest REE-carbonatite deposits are Bayan Obo, Mountain Pass, Maoniuping, and Mount Weld. Vein deposits of
thorium Thorium is a chemical element; it has symbol Th and atomic number 90. Thorium is a weakly radioactive light silver metal which tarnishes olive grey when it is exposed to air, forming thorium dioxide; it is moderately soft, malleable, and ha ...
,
fluorite Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon. The Mohs scal ...
, or
rare-earth element The rare-earth elements (REE), also called the rare-earth metals or rare earths, and sometimes the lanthanides or lanthanoids (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), are a set o ...
s may be associated with carbonatites and may be hosted internal to or within the metasomatized aureole of a carbonatite. As an example, the Palabora complex of
South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...
has produced significant copper (as
chalcopyrite Chalcopyrite ( ) is a copper iron sulfide mineral and the most abundant copper ore mineral. It has the chemical formula CuFeS2 and crystallizes in the tetragonal system. It has a brassy to golden yellow color and a Mohs scale, hardness of 3.5 to 4 ...
, bornite and chalcocite), apatite, vermiculate along with lesser magnetite, linnaeite (
cobalt Cobalt is a chemical element; it has Symbol (chemistry), symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. ...
),
baddeleyite Baddeleyite is a rare zirconium oxide mineral (ZrO2 or zirconia), occurring in a variety of monoclinic prismatic crystal forms. It is transparent to translucent, has high Index of refraction, indices of refraction, and ranges from colorless to yel ...
(zirconium–hafnium), and by-product
gold Gold is a chemical element; it has chemical symbol Au (from Latin ) and atomic number 79. In its pure form, it is a brightness, bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal ...
,
silver Silver is a chemical element; it has Symbol (chemistry), symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. ...
,
nickel Nickel is a chemical element; it has symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive, but large pieces are slo ...
and
platinum Platinum is a chemical element; it has Symbol (chemistry), symbol Pt and atomic number 78. It is a density, dense, malleable, ductility, ductile, highly unreactive, precious metal, precious, silverish-white transition metal. Its name origina ...
.


Popular culture

The generic stone found in the
video game A video game or computer game is an electronic game that involves interaction with a user interface or input device (such as a joystick, game controller, controller, computer keyboard, keyboard, or motion sensing device) to generate visual fe ...
''
Minecraft ''Minecraft'' is a 2011 sandbox game developed and published by the Swedish video game developer Mojang Studios. Originally created by Markus Persson, Markus "Notch" Persson using the Java (programming language), Java programming language, the ...
'' has been theorised to be carbonatite.


References


Sources

* Duncan R. K., Willett G. C. (1990) – Mount Weld Carbonatite: in Hughes F. E. (Ed.), 1990 ''Geology of the Mineral Deposits of Australia & Papua New Guinea'' The AusIMM, Melbourne Mono 14, v. 1 pp. 591–597. * * * *
Bolivian carbonatite occurrences


External links










Phosphate deposits of Australia, Mount Weld Carbonatite

Description of the Mount Weld Carbonatite

Blue River Carbonatites, British Columbia, Canada

Video of molten carbonatite lava flow eruptions at Ol Doinyo Lengai volcano
{{Rock type Igneous rocks