Cleusonite
Encyclopedia
Cleusonite is a member of the crichtonite group of minerals with a chemical formula of (Pb,Sr)(U4+,U6+)(Fe2+,Zn)(Ti,Fe2+,Fe3+)18(O,OH)38. This group of minerals contains approximately thirteen complex metal titanates. The structures of minerals of this group is complicated by frequent fine-scale twinning
and metamictization
due to radioactive elements. The crichtonite group consists of members of related mineral species of the type A{BC2D6E12}O38 which are characterized by their predominant cations (as seen in crichtonite (Sr), senaite (Pb), davidite
(REE + U), landauite (Na), loveringite
(Ca), lindsleyite (Ba), and mathiasite (K).
, chlorite
, calcite
, albite
, microcline
, tourmaline
, fluorapatite
, zircon
, ilmenite
, hematite
, titanite
, pyrite
, chalcopyrite
, tennantite
, rutile
, crichtonite, monazite
-(Ce), and native gold.
Clausthalite
, chalcopyrite
, and uraninite
are also found in the form of inclusions in cleusonite.
end-member senaite of the crichtonite group was determined in 1976 by Grey & Lloyd. The structure of the other members of the crichtonite group is similar and corresponds to the formula AM21O38.
The crystals of cleusonite consist of multiple rhombohedra and hexagonal prisms that are twinned. The crystal system is a trigonal - rhombohedral class 3 and has space group of R.
.
Cleusonite crystals are usually metamict black semimetallic prismatic and associated with quartz
.
ic series of the Mont Fort and Siviez-Mischabel Nappes in Valais
, Switzerland
(Cleuson and Bella Tolla summit), and named after the type locality
. Cleusonite is found first in metamorphic rock
s of the central Swiss Alps
with the type locality being Oligocene
-Miocene
alpine cleft veins near Cleuson, Val de Nendaz, Valais and secondly in gneisses and crosscutting alpine veins near the Bella Tolla summit, also in Valais. In the Bella Tolla summit it is found in the form of hematite
-stained flattened aggregates with quartz
, albite
, baryte, chalcopyrite
, uraninite
, tennantite
, pyrite
, magnetite
, cinnabar
, and malachite
. The name cleusonite is used for the previously described “uranium-rich senaite” from Alinci
, Macedonia
and the "plumbodavidite" from Huanglongpu, China
. Cleusonite is radioactive.
Crystal twinning
Crystal twinning occurs when two separate crystals share some of the same crystal lattice points in a symmetrical manner. The result is an intergrowth of two separate crystals in a variety of specific configurations. A twin boundary or composition surface separates the two crystals....
and 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...
due to radioactive elements. The crichtonite group consists of members of related mineral species of the type A{BC2D6E12}O38 which are characterized by their predominant cations (as seen in crichtonite (Sr), senaite (Pb), davidite
Davidite
Davidite is a rare earth oxide mineral with chemical end members La and Ce. It exists in two forms:*Davidite- 20O38 discovered at Radium Hill mine, South Australia in 1906 and named for Australian geologist Tenatt William Edgeworth David .*Davidite- 20O38 first described in 1960 from Vemork,...
(REE + U), landauite (Na), loveringite
Loveringite
Loveringite is a rare metallic oxide mineral of the crichtonite group with the chemical formula 21O38. It is a late-stage magmatic mineral, formed in the residual melt of mafic layered intrusions in either the olivine-chromite, pyroxene, or plagioclase-rich layers.-Discovery and...
(Ca), lindsleyite (Ba), and mathiasite (K).
Composition
The chemical formula of cleusonite is (Pb,Sr)(U4+,U6+)(Fe2+,Zn)2(Ti,Fe2+,Fe3+)18(O,OH)38. The following minerals are also found in the veins of cleusonite; quartzQuartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
, chlorite
Chlorite group
The chlorites are a group of phyllosilicate minerals. Chlorites can be described by the following four endmembers based on their chemistry via substitution of the following four elements in the silicate lattice; Mg, Fe, Ni, and Mn....
, calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
, albite
Albite
Albite is a plagioclase feldspar mineral. It is the sodium endmember of the plagioclase solid solution series. As such it represents a plagioclase with less than 10% anorthite content. The pure albite endmember has the formula NaAlSi3O8. It is a tectosilicate. Its color is usually pure white, hence...
, microcline
Microcline
Microcline is an important igneous rock-forming tectosilicate mineral. It is a potassium-rich alkali feldspar. Microcline typically contains minor amounts of sodium. It is common in granite and pegmatites. Microcline forms during slow cooling of orthoclase; it is more stable at lower temperatures...
, tourmaline
Tourmaline
Tourmaline is a crystal boron silicate mineral compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is classified as a semi-precious stone and the gem comes in a wide variety of colors...
, fluorapatite
Fluorapatite
Fluorapatite, often with the alternate spelling of fluoroapatite, is a mineral with the formula Ca53F . Fluorapatite is a hard crystalline solid. Although samples can have various color , the pure mineral is colorless as expected for a material lacking transition metals...
, zircon
Zircon
Zircon is a mineral belonging to the group of nesosilicates. Its chemical name is zirconium silicate and its corresponding chemical formula is ZrSiO4. A common empirical formula showing some of the range of substitution in zircon is 1–x4x–y...
, ilmenite
Ilmenite
Ilmenite 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....
, hematite
Hematite
Hematite, also spelled as haematite, is the mineral form of iron oxide , one of several iron oxides. Hematite crystallizes in the rhombohedral system, and it has the same crystal structure as ilmenite and corundum...
, titanite
Titanite
Titanite, or sphene , is a calcium titanium nesosilicate mineral, CaTiSiO5. Trace impurities of iron and aluminium are typically present...
, pyrite
Pyrite
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...
, chalcopyrite
Chalcopyrite
Chalcopyrite is a copper iron sulfide mineral that crystallizes in the tetragonal system. It has the chemical composition CuFeS2. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green tinged black.On exposure to air, chalcopyrite...
, tennantite
Tennantite
Tennantite is a copper arsenic sulfosalt mineral. Its chemical formula is Cu12As4S13. It is grey-black, steel-gray, iron-gray or black in color. A closely related mineral, tetrahedrite has antimony substituting for arsenic and the two form a solid solution series. The two have very similar...
, rutile
Rutile
Rutile is a mineral composed primarily of titanium dioxide, TiO2.Rutile is the most common natural form of TiO2. Two rarer polymorphs of TiO2 are known:...
, crichtonite, monazite
Monazite
Monazite is a reddish-brown phosphate mineral containing rare earth metals. It occurs usually in small isolated crystals. There are actually at least four different kinds of monazite, depending on relative elemental composition of the mineral:...
-(Ce), and native gold.
Clausthalite
Clausthalite
Clausthalite is a lead selenide mineral, PbSe. It forms a solid solution series with galena PbS.-Occurrence:It occurs in low-sulfur hydrothermal deposits with other selenides and in mercury deposits...
, chalcopyrite
Chalcopyrite
Chalcopyrite is a copper iron sulfide mineral that crystallizes in the tetragonal system. It has the chemical composition CuFeS2. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green tinged black.On exposure to air, chalcopyrite...
, and uraninite
Uraninite
Uraninite is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO2, but also contains UO3 and oxides of lead, thorium, and rare earth elements...
are also found in the form of inclusions in cleusonite.
Structure
The structure of the leadLead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
end-member senaite of the crichtonite group was determined in 1976 by Grey & Lloyd. The structure of the other members of the crichtonite group is similar and corresponds to the formula AM21O38.
The crystals of cleusonite consist of multiple rhombohedra and hexagonal prisms that are twinned. The crystal system is a trigonal - rhombohedral class 3 and has space group of R.
Physical properties
Cleusonite is seen as a black opaque cm-sized tabular crystal with a bright sub-metallic luster. It does not have any cleavage and has a density of about 4.74(4) g/cm3. The calculated density may vary from 5.02(6) (for untreated crystals) to 5.27(5) (heat-treated crystals); the variations are caused by the cell swelling due to the metamictizationMetamictization
Metamictization is a natural process resulting in the gradual and ultimately complete destruction of a mineral's crystal structure, leaving the mineral amorphous...
.
Cleusonite crystals are usually metamict black semimetallic prismatic and associated with quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
.
Geological occurrence characteristics
It was found at two occurrences in greenschist facies metamorphosed gneissGneiss
Gneiss is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks.-Etymology:...
ic series of the Mont Fort and Siviez-Mischabel Nappes in Valais
Valais
The Valais is one of the 26 cantons of Switzerland in the southwestern part of the country, around the valley of the Rhône from its headwaters to Lake Geneva, separating the Pennine Alps from the Bernese Alps. The canton is one of the drier parts of Switzerland in its central Rhône valley...
, Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
(Cleuson and Bella Tolla summit), and named after the type locality
Type locality (geology)
Type locality , also called type area or type locale, is the where a particular rock type, stratigraphic unit, fossil or mineral species is first identified....
. Cleusonite is found first 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 of the central Swiss Alps
Alps
The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....
with the type locality being Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
-Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
alpine cleft veins near Cleuson, Val de Nendaz, Valais and secondly in gneisses and crosscutting alpine veins near the Bella Tolla summit, also in Valais. In the Bella Tolla summit it is found in the form of hematite
Hematite
Hematite, also spelled as haematite, is the mineral form of iron oxide , one of several iron oxides. Hematite crystallizes in the rhombohedral system, and it has the same crystal structure as ilmenite and corundum...
-stained flattened aggregates with quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
, albite
Albite
Albite is a plagioclase feldspar mineral. It is the sodium endmember of the plagioclase solid solution series. As such it represents a plagioclase with less than 10% anorthite content. The pure albite endmember has the formula NaAlSi3O8. It is a tectosilicate. Its color is usually pure white, hence...
, baryte, chalcopyrite
Chalcopyrite
Chalcopyrite is a copper iron sulfide mineral that crystallizes in the tetragonal system. It has the chemical composition CuFeS2. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green tinged black.On exposure to air, chalcopyrite...
, uraninite
Uraninite
Uraninite is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO2, but also contains UO3 and oxides of lead, thorium, and rare earth elements...
, tennantite
Tennantite
Tennantite is a copper arsenic sulfosalt mineral. Its chemical formula is Cu12As4S13. It is grey-black, steel-gray, iron-gray or black in color. A closely related mineral, tetrahedrite has antimony substituting for arsenic and the two form a solid solution series. The two have very similar...
, pyrite
Pyrite
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...
, magnetite
Magnetite
Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. The chemical IUPAC name is iron oxide and the common chemical name is ferrous-ferric oxide. The formula for magnetite may also be written as FeO·Fe2O3, which is one part...
, cinnabar
Cinnabar
Cinnabar or cinnabarite , is the common ore of mercury.-Word origin:The name comes from κινναβαρι , a Greek word most likely applied by Theophrastus to several distinct substances...
, and malachite
Malachite
Malachite is a copper carbonate mineral, with the formula Cu2CO32. This green-colored mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses. Individual crystals are rare but do occur as slender to acicular prisms...
. The name cleusonite is used for the previously described “uranium-rich senaite” from Alinci
Alinci
Alinci is a small village in Macedonia between Mogila and Musinci that spreads from the Bitola to the Prilep provence. There is a small population in Alinci and a small number of houses than there once were with a bigger population. Alinci also has much produce in the farms such as fruit, vegetable...
, Macedonia
Republic of Macedonia
Macedonia , officially the Republic of Macedonia , is a country located in the central Balkan peninsula in Southeast Europe. It is one of the successor states of the former Yugoslavia, from which it declared independence in 1991...
and the "plumbodavidite" from Huanglongpu, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
. Cleusonite is radioactive.