Chamosite
Encyclopedia
Chamosite is the Fe2+end member of the chlorite group
. A hydrous aluminium silicate
of iron
, which is produced in an environment of low to moderate grade of metamorphosed
iron deposits, as gray or black crystals in oolitic
iron ore. Like other chlorites, it is a product of the hydrothermal alteration of pyroxene
s, amphibole
s and biotite
in igneous rock
. The composition of chlorite is often related to that of the original igneous mineral so that more fe-rich chlorites are commonly found as replacements of the fe-rich ferromagnesian minerals (Deer et al., 1992).
, France
, discovered chamosite. The new mineral was found in an area of low to moderate grade metamorphosed iron deposit. Early chamosite (which are chlorites) stirred some controversy after they discovered to have possessed the structure of kaolin rather than chlorite. But further research proved that chamosite was largely in existence with another phyllosilicate called berthierine (which has a kaolin type structure) which was rather difficult to distinguish from chamosites. Chamosite is named after the municipality of Chamoson
, between Sion
and Martigny, the canton of Valais
, Switzerland
.
-energy-dispersive X-ray spectroscopy
(SEM-EDS) indicates positive correlation between %B and Fe/(Fe + Mg) (Ryan and Hillier, 2002). The chamosite structure is very similar to typical chlorite in which they are alternated regular layers with tetrahedral and tri-octahedral components(M.L. Rivas Sanchez et al., 2006). Its 2:1 layer structure is similar to that of mica
, with a basal spacing of 14 Å. (M.L. Rivas Sanchez et al., 2006). In most common chlorites, there are 12.0 octahedral cations per O20(OH)16 and approximately equivalent amounts of aluminium in tetrahedral and octahedral sites [e.g. the magnesia chlorite, clinochlore, (Mg10Al2)(Si6Al2O20)(OH)16] (Deer et al., 1992).
s, illite
s, montmorillonite
s and vermiculite
, and refractive indices are higher than those of kaolinite (Deer et al. 1992). The chamosite spectra shows the reflection d=7.18 Å (main value of the chlorite) and the reflection d=14.4 Å (that confirms the presence of chlorite) (M.L. Rivas Sanchez et al., 2006).
, Nigeria
was studied by Akande and Mucke (1993), and they concluded that the carbonate discovered with associated chamosite was formed in a shallow marine subtidal to intertidal environment developed during periods of rise and fall in sea level. Formation of chamosite bearing oolite
s record periods of increasing wave energy corresponding to storm conditions between quiet shallow marine sedimentation,(Akande and Mucke, 1993). Chamosite is a mineral from which elements may be extracted for commercial purpose. Xuanwei City in Yunnan
Province has one of the highest lung cancer mortality rates in China (Dai, S. et al., 2008). This epidemic had long been blamed on hydrocarbons released from the burning of coal. Dai, S. et al. (2008) conducted a mineralogical and geochemical study of coal from two coal mines in this region, and identified chamosite as one of the main minerals in the coal.
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....
. A hydrous aluminium silicate
Aluminium silicate
Aluminium silicate has the chemical formula 2SiO3. It has a density of 2.8 to 2.9 g/cm³, a vitreous lustre, a refractive index of 1.56, a Mohs hardness of 4.5-7.5 , and can have orthorhombic crystallography...
of iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
, which is produced in an environment of low to moderate grade of metamorphosed
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...
iron deposits, as gray or black crystals in oolitic
Oolite
Oolite is a sedimentary rock formed from ooids, spherical grains composed of concentric layers. The name derives from the Hellenic word òoion for egg. Strictly, oolites consist of ooids of diameter 0.25–2 mm; rocks composed of ooids larger than 2 mm are called pisolites...
iron ore. Like other chlorites, it is a product of the hydrothermal alteration of pyroxene
Pyroxene
The pyroxenes are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. They share a common structure consisting of single chains of silica tetrahedra and they crystallize in the monoclinic and orthorhombic systems...
s, amphibole
Amphibole
Amphibole is the name of an important group of generally dark-colored rock-forming inosilicate minerals, composed of double chain tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures.-Mineralogy:...
s and biotite
Biotite
Biotite is a common phyllosilicate mineral within the mica group, with the approximate chemical formula . More generally, it refers to the dark mica series, primarily a solid-solution series between the iron-endmember annite, and the magnesium-endmember phlogopite; more aluminous endmembers...
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...
. The composition of chlorite is often related to that of the original igneous mineral so that more fe-rich chlorites are commonly found as replacements of the fe-rich ferromagnesian minerals (Deer et al., 1992).
History
In 1820, Pierre Bertier; a mineralogist and mining engineer from NemoursNemours
Nemours is a commune in the Seine-et-Marne department in the Île-de-France region in north-central France.-Geography:Nemours is located on the Loing and its canal, c...
, France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, discovered chamosite. The new mineral was found in an area of low to moderate grade metamorphosed iron deposit. Early chamosite (which are chlorites) stirred some controversy after they discovered to have possessed the structure of kaolin rather than chlorite. But further research proved that chamosite was largely in existence with another phyllosilicate called berthierine (which has a kaolin type structure) which was rather difficult to distinguish from chamosites. Chamosite is named after the municipality of Chamoson
Chamoson
Chamoson is a municipality in the district of Conthey in the canton of Valais in Switzerland.-History:Chamoson is first mentioned in 1050 as Camusia. In 1233 it was mentioned as Scamosun.-Geography:...
, between Sion
Sion, Switzerland
Sion is the capital of the Swiss canton of Valais. it had a population of .Landmarks include the Basilique de Valère and Château de Tourbillon. Sion has an airfield for civilian and military use, which, because of its location in a valley, causes a reasonable amount of noise pollution. FC Sion...
and Martigny, the canton of 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....
.
Structure
X-ray diffraction(XRD) indicates that the proportion of 7 Å B layers in bertherine-chamosite ranges from 5 to 28%, and chemical analysis by scanning electron microscopeScanning electron microscope
A scanning electron microscope is a type of electron microscope that images a sample by scanning it with a high-energy beam of electrons in a raster scan pattern...
-energy-dispersive X-ray spectroscopy
Energy-dispersive X-ray spectroscopy
Energy-dispersive X-ray spectroscopy is an analytical technique used for the elemental analysis or chemical characterization of a sample. It relies on the investigation of an interaction of a some source of X-ray excitation and a sample...
(SEM-EDS) indicates positive correlation between %B and Fe/(Fe + Mg) (Ryan and Hillier, 2002). The chamosite structure is very similar to typical chlorite in which they are alternated regular layers with tetrahedral and tri-octahedral components(M.L. Rivas Sanchez et al., 2006). Its 2:1 layer structure is similar to that of mica
Mica
The mica group of sheet silicate minerals includes several closely related materials having highly perfect basal cleavage. All are monoclinic, with a tendency towards pseudohexagonal crystals, and are similar in chemical composition...
, with a basal spacing of 14 Å. (M.L. Rivas Sanchez et al., 2006). In most common chlorites, there are 12.0 octahedral cations per O20(OH)16 and approximately equivalent amounts of aluminium in tetrahedral and octahedral sites [e.g. the magnesia chlorite, clinochlore, (Mg10Al2)(Si6Al2O20)(OH)16] (Deer et al., 1992).
Physical properties
Chamosite has a laminar shape, sheets measure from 20 to 200 μm (M.L. Rivas Sanchez et al., 2006). Chamosite may be greenish gray or brown in color. The cleavage are length-slow, the orientation may be α ∧ c=small, β=b, γ ∧ α=small, optic plane= [0 10] (Heinrich, 1965) and has good cleavage on the {011} axis. It has a dull luster and grayish green streak. Birefringence is much lower than that of the micaMica
The mica group of sheet silicate minerals includes several closely related materials having highly perfect basal cleavage. All are monoclinic, with a tendency towards pseudohexagonal crystals, and are similar in chemical composition...
s, illite
Illite
Illite is a non-expanding, clay-sized, micaceous mineral. Illite is a phyllosilicate or layered alumino-silicate. Its structure is constituted by the repetition of tetrahedron – octahedron – tetrahedron layers. The interlayer space is mainly occupied by poorly hydrated potassium cations...
s, montmorillonite
Montmorillonite
Montmorillonite is a very soft phyllosilicate group of minerals that typically form in microscopic crystals, forming a clay. It is named after Montmorillon in France. Montmorillonite, a member of the smectite family, is a 2:1 clay, meaning that it has 2 tetrahedral sheets sandwiching a central...
s and vermiculite
Vermiculite
Vermiculite is a natural mineral that expands with the application of heat. The expansion process is called exfoliation and it is routinely accomplished in purpose-designed commercial furnaces. Vermiculite is formed by weathering or hydrothermal alteration of biotite or phlogopite...
, and refractive indices are higher than those of kaolinite (Deer et al. 1992). The chamosite spectra shows the reflection d=7.18 Å (main value of the chlorite) and the reflection d=14.4 Å (that confirms the presence of chlorite) (M.L. Rivas Sanchez et al., 2006).
Geologic occurrence
Chamosite is a relatively uncommon mineral in nature. Since its discovery in Chamoson, only about 15 localities around the world are known to be associated with iron deposits. Chamosite may be found in occurrence with other chlorite minerals. In recent years, berthierine; a more abundant chlorite, was discovered in occurrence with chamosite in the iron deposit of Pena Colorada, Mexico. Chamosite is related to the beginning of a hydrothermal phase and occurs mainly in a mineralized breccia type stock-work in which it fills open spaces and replaces the hot rock through fissures (M.L. Rivas Sanchez et al., 2006). The Mamu-Nkporo formation in the locality of OkigweOkigwe
-See also:Roman Catholic Diocese of Okigwe...
, Nigeria
Nigeria
Nigeria , officially the Federal Republic of Nigeria, is a federal constitutional republic comprising 36 states and its Federal Capital Territory, Abuja. The country is located in West Africa and shares land borders with the Republic of Benin in the west, Chad and Cameroon in the east, and Niger in...
was studied by Akande and Mucke (1993), and they concluded that the carbonate discovered with associated chamosite was formed in a shallow marine subtidal to intertidal environment developed during periods of rise and fall in sea level. Formation of chamosite bearing oolite
Oolite
Oolite is a sedimentary rock formed from ooids, spherical grains composed of concentric layers. The name derives from the Hellenic word òoion for egg. Strictly, oolites consist of ooids of diameter 0.25–2 mm; rocks composed of ooids larger than 2 mm are called pisolites...
s record periods of increasing wave energy corresponding to storm conditions between quiet shallow marine sedimentation,(Akande and Mucke, 1993). Chamosite is a mineral from which elements may be extracted for commercial purpose. Xuanwei City in Yunnan
Yunnan
Yunnan is a province of the People's Republic of China, located in the far southwest of the country spanning approximately and with a population of 45.7 million . The capital of the province is Kunming. The province borders Burma, Laos, and Vietnam.Yunnan is situated in a mountainous area, with...
Province has one of the highest lung cancer mortality rates in China (Dai, S. et al., 2008). This epidemic had long been blamed on hydrocarbons released from the burning of coal. Dai, S. et al. (2008) conducted a mineralogical and geochemical study of coal from two coal mines in this region, and identified chamosite as one of the main minerals in the coal.