Balangeroite
Encyclopedia
Balangeroite is found in one of the most important chrysotile
Chrysotile
Chrysotile or white asbestos is the most commonly encountered form of asbestos, accounting for approximately 95% of the asbestos in place in the United States and a similar proportion in other countries. It is a soft, fibrous silicate mineral in the serpentine group of phyllosilicates; as such, it...

 mines in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, the Balangero Serpentinite
Serpentinite
Serpentinite is a rock composed of one or more serpentine group minerals. Minerals in this group are formed by serpentinization, a hydration and metamorphic transformation of ultramafic rock from the Earth's mantle...

. It is considered an asbestiform
Asbestiform
Asbestiform implies a particular kind of fibrosity in which fibers have high tensile strength and flexibility....

 in an assemblage of other mineral phases like chrysotile, 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...

 and Fe-Ni alloys. In addition to its fibrous occurrence, balangeroite's association with chrysotile raises concerns about its potential toxicity when its fibers are inhaled.

Introduction

Balangeroite is classified as belonging to one of the two asbestiform
Asbestiform
Asbestiform implies a particular kind of fibrosity in which fibers have high tensile strength and flexibility....

 silicate
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...

 groups, the Serpentine group. It is intergrown with the dominant member of the serpentinite
Serpentinite
Serpentinite is a rock composed of one or more serpentine group minerals. Minerals in this group are formed by serpentinization, a hydration and metamorphic transformation of ultramafic rock from the Earth's mantle...

, Chrysotile
Chrysotile
Chrysotile or white asbestos is the most commonly encountered form of asbestos, accounting for approximately 95% of the asbestos in place in the United States and a similar proportion in other countries. It is a soft, fibrous silicate mineral in the serpentine group of phyllosilicates; as such, it...

, often associated with tremolite
Tremolite
Tremolite is a member of the amphibole group of silicate minerals with composition: Ca2Mg5Si8O222. Tremolite forms by metamorphism of sediments rich in dolomite and quartz. Tremolite forms a series with actinolite and ferro-actinolite. Pure magnesium tremolite is creamy white, but the color grades...

 (a contaminant of Chrysotile), which is classified as part of the Amphibole group, the other asbestiform
Asbestiform
Asbestiform implies a particular kind of fibrosity in which fibers have high tensile strength and flexibility....

 silicate
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...

 Massive serpentines are economically important for providing building material. The fibrous nature of Chrysotile
Chrysotile
Chrysotile or white asbestos is the most commonly encountered form of asbestos, accounting for approximately 95% of the asbestos in place in the United States and a similar proportion in other countries. It is a soft, fibrous silicate mineral in the serpentine group of phyllosilicates; as such, it...

 is particularly valuable for thermal insulation purposes, fireproofing etc. Tremolite
Tremolite
Tremolite is a member of the amphibole group of silicate minerals with composition: Ca2Mg5Si8O222. Tremolite forms by metamorphism of sediments rich in dolomite and quartz. Tremolite forms a series with actinolite and ferro-actinolite. Pure magnesium tremolite is creamy white, but the color grades...

 contaminated Chrysotile
Chrysotile
Chrysotile or white asbestos is the most commonly encountered form of asbestos, accounting for approximately 95% of the asbestos in place in the United States and a similar proportion in other countries. It is a soft, fibrous silicate mineral in the serpentine group of phyllosilicates; as such, it...

 shows that the toxicity of the asbestos
Asbestos
Asbestos is a set of six naturally occurring silicate minerals used commercially for their desirable physical properties. They all have in common their eponymous, asbestiform habit: long, thin fibrous crystals...

 is due to the presence of Tremolite
Tremolite
Tremolite is a member of the amphibole group of silicate minerals with composition: Ca2Mg5Si8O222. Tremolite forms by metamorphism of sediments rich in dolomite and quartz. Tremolite forms a series with actinolite and ferro-actinolite. Pure magnesium tremolite is creamy white, but the color grades...

 and not the entire mass of the Chrysotile
Chrysotile
Chrysotile or white asbestos is the most commonly encountered form of asbestos, accounting for approximately 95% of the asbestos in place in the United States and a similar proportion in other countries. It is a soft, fibrous silicate mineral in the serpentine group of phyllosilicates; as such, it...

. Recent publications by Turci have drawn some conclusions that Balangeroite contaminated Chrysotile
Chrysotile
Chrysotile or white asbestos is the most commonly encountered form of asbestos, accounting for approximately 95% of the asbestos in place in the United States and a similar proportion in other countries. It is a soft, fibrous silicate mineral in the serpentine group of phyllosilicates; as such, it...

 does have some areas of concern and can be attributed to the overall toxicity of the airborne fibers in the Balangero mine. Therefore, it cannot be compared to tremolite
Tremolite
Tremolite is a member of the amphibole group of silicate minerals with composition: Ca2Mg5Si8O222. Tremolite forms by metamorphism of sediments rich in dolomite and quartz. Tremolite forms a series with actinolite and ferro-actinolite. Pure magnesium tremolite is creamy white, but the color grades...

 or croidolite in level of pathogenicity as the two have been proven by autopsies and biopsies to be present in the bodies of the people exposed to their fibers.

Composition

The chemical formula for Balangeroite is
(Mg, Fe2+, Fe3+, Mn2+)42Si16O54(OH)40 and it has been calculated as shown in the diagram below by Compagnoni as follows:
Table 1a. Chemical Analysis of Balangeroite
SiO2 28.37
TiO2 0.03
Al2O3 0.27
Fe2O3 8.89
Cr2O3 0.03
FeO 16.95
MnO 3.59
MgO 31.81
CaO 0.13
H2O 9.93
Total 100.00


Wet Chemical, X-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...

 Fluorescence
Fluorescence
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation of a different wavelength. It is a form of luminescence. In most cases, emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation...

 and electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...

 microprobe
Microprobe
A microprobe is an instrument that applies a stable and well-focused beam of charged particles to a sample.-Types:When the primary beam consists of accelerated electrons, the probe is termed an electron microprobe, when the primary beam consists of accelerated ions, the term Ion Microprobe is used...

 analysis
Analysis
Analysis is the process of breaking a complex topic or substance into smaller parts to gain a better understanding of it. The technique has been applied in the study of mathematics and logic since before Aristotle , though analysis as a formal concept is a relatively recent development.The word is...

 were used to deduce the composition of Balangeroite. The common intergrowth with Chrysotile
Chrysotile
Chrysotile or white asbestos is the most commonly encountered form of asbestos, accounting for approximately 95% of the asbestos in place in the United States and a similar proportion in other countries. It is a soft, fibrous silicate mineral in the serpentine group of phyllosilicates; as such, it...

 proved to be valuable in providing better chemical resolution as portrayed in table 1. The results varied due to submicroscopic intergrowths or zoning
Zoning
Zoning is a device of land use planning used by local governments in most developed countries. The word is derived from the practice of designating permitted uses of land based on mapped zones which separate one set of land uses from another...

. From the wet
Wet
Wet may refer to:* The condition of being liquid or being covered in liquid* Adequately wet, environmental term referring to asbestos-containing material that is sufficiently mixed or penetrated with liquid to prevent the release of particulates...

 chemical analysis
Analysis
Analysis is the process of breaking a complex topic or substance into smaller parts to gain a better understanding of it. The technique has been applied in the study of mathematics and logic since before Aristotle , though analysis as a formal concept is a relatively recent development.The word is...

, there was 9.5% average weight loss after calcination
Calcination
Calcination is a thermal treatment process applied to ores and other solid materials to bring about a thermal decomposition, phase transition, or removal of a volatile fraction. The calcination process normally takes place at temperatures below the melting point of the product materials...

 at 1000°C, due to the presence of water. This was calculated as the difference from 100% of microprobe
Microprobe
A microprobe is an instrument that applies a stable and well-focused beam of charged particles to a sample.-Types:When the primary beam consists of accelerated electrons, the probe is termed an electron microprobe, when the primary beam consists of accelerated ions, the term Ion Microprobe is used...

 results, with the assumption that large quantities of material usually contain some impurities, and the possible oxidation of Fe2+ under heating. A ratio of Fe2+/Fe3+ = 2.12 was obtained and on the basis of the known volume and density, the empirical
Empirical
The word empirical denotes information gained by means of observation or experimentation. Empirical data are data produced by an experiment or observation....

 formula
Formula
In mathematics, a formula is an entity constructed using the symbols and formation rules of a given logical language....

 for the unit cell was derived
(Mg 25.70 Fe2+7.69 Fe3+3.63 Mn2+1.65 Al0.17 Ca0.07 Cr0.01 Ti0.01) total= 38.93 Si15.38O53.66(OH)35.92.

Structure

Balangeroite is based on an octahedral build that consists of channels that are filled by chains of silicate tetrahedra grouped in three and 4 rows running along the fiber axis. Balangeroite is 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...

 to Gageite.

In contrast to Chrysotile
Chrysotile
Chrysotile or white asbestos is the most commonly encountered form of asbestos, accounting for approximately 95% of the asbestos in place in the United States and a similar proportion in other countries. It is a soft, fibrous silicate mineral in the serpentine group of phyllosilicates; as such, it...

, however, Balangeroite has more metal ions than Silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

 ions and might be in some cases seen as complex Iron Oxide
Iron oxide
Iron oxides are chemical compounds composed of iron and oxygen. All together, there are sixteen known iron oxides and oxyhydroxides.Iron oxides and oxide-hydroxides are widespread in nature, play an important role in many geological and biological processes, and are widely utilized by humans, e.g.,...

 containing some type of silicate structure in its framework. The surrounding fluid takes in a large number of the cations which are octahedrally coordinated, which unlike amphiboles, may be easily removed. As a consequence, the Mg and Fe are released forcing the silicate
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...

 structure to become loosely bound and therefore pass into solution. Further tests have been conducted on Balangeroite's ecopersistence and it showed fairly low eco-persistence at neutral pH. Further studies were conducted by imitating weathering in an experiment to predict if weathered fibers retain the toxic potential present in freshly extracted fibers. The tests proved that Balangeroite showed removal of Mg and Si which shows a continuous structural severance which extends far beyond the surface.

Physical properties

Balangeroite can develop as loose fibers or compact when in large volumes which can be prismatic
Prism (geometry)
In geometry, a prism is a polyhedron with an n-sided polygonal base, a translated copy , and n other faces joining corresponding sides of the two bases. All cross-sections parallel to the base faces are the same. Prisms are named for their base, so a prism with a pentagonal base is called a...

. Antigorite flakes are included in relict
Relict
A relict is a surviving remnant of a natural phenomenon.* In biology a relict is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas....

 prismatic
Prism (geometry)
In geometry, a prism is a polyhedron with an n-sided polygonal base, a translated copy , and n other faces joining corresponding sides of the two bases. All cross-sections parallel to the base faces are the same. Prisms are named for their base, so a prism with a pentagonal base is called a...

 Balangeroite, while TEM
Transmission electron microscopy
Transmission electron microscopy is a microscopy technique whereby a beam of electrons is transmitted through an ultra thin specimen, interacting with the specimen as it passes through...

 observation shows that fibrous Balangeroite is partially replaced by Chrysotile
Chrysotile
Chrysotile or white asbestos is the most commonly encountered form of asbestos, accounting for approximately 95% of the asbestos in place in the United States and a similar proportion in other countries. It is a soft, fibrous silicate mineral in the serpentine group of phyllosilicates; as such, it...

. The fibers run a couple of centimeters in the [001].
Table 2. Physical Properties of Balangeroite.
Chemical Formula (Mg, Fe²⁺, Fe ³⁺, Mn²⁺) 42 Si16 O54 (OH) 40
Crystal Data Monoclinic, 2/m point group, elongated along [001]
Color Pleichroism; dark brown and yellow brown parallel and perpendicular to [001] successively
Opacity Transparent only in thin sections
Cleavage One or more {hk0} are very good
Tenacity Brittle, hardness is not determined (n.d)
Luster Vitreous- greasy
Optical Class Biaxial (-), due to its isostructural nature with gageite, it should be biaxial but due to its texture, it only has 1 refractive index
Refractive index
In optics the refractive index or index of refraction of a substance or medium is a measure of the speed of light in that medium. It is expressed as a ratio of the speed of light in vacuum relative to that in the considered medium....

.
Space group
Space group
In mathematics and geometry, a space group is a symmetry group, usually for three dimensions, that divides space into discrete repeatable domains.In three dimensions, there are 219 unique types, or counted as 230 if chiral copies are considered distinct...

P2/n
Density 2.98 g/cm3 measure on a torsion
Torsion spring
A torsion spring is a spring that works by torsion or twisting; that is, a flexible elastic object that stores mechanical energy when it is twisted. The amount of force it exerts is proportional to the amount it is twisted. There are two types...

 balance

Geologic occurrences

The piemonte zone, remnant of the Piemontese
Piemontese
Piemontese* Guardia Piemontese* Bonarda Piemontese* Tarocco Piemontese* Piedmontese language...

 Ocean
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...

 from the late Jurassic
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 161.2 ± 4.0 to 145.5 ± 4.0 million years ago , which is preserved in Upper Jurassic strata. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age...

, is home to the majority of the serpentines of the Western Alps. Balangero mine is located in the Lanzu Ultramafic Massif
Massif
In geology, a massif is a section of a planet's crust that is demarcated by faults or flexures. In the movement of the crust, a massif tends to retain its internal structure while being displaced as a whole...

 which is in the inner part of the piemonte zone. The Lanzu Ultramafic Massif is believed to have been involved in the subduction
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...

 processes that were affiliated with the closure of the Piemontese Ocean in the late
Late
Late may refer to:* A deceased person or thing* Late , a 2000 album by The 77s* Late!, a pseudonym used by Dave Grohl on his Pocketwatch album* Late , an underground rapper from Wolverhampton* "Late" , a song by Blue Angel...

 Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

. The earliest generation of metamorphic veins and in particular type 1 Vein that constitute relict prismatic Balangeroite (often includes antigorite flakes) were formed during prograde high pressure metamorphism. Fibrous Balangeroite is limited to the serpentine-infested rim of the northern Lanzu Ultramafic Massif, with its abundance in the inactive Balangero asbestos mine, where it was discovered.
Balangeroite was named after the location in which it was discovered. It was brought to the attention of Robert Compagnoni and his colleagues at the Universitia Della Calabria, Cosenza Italy by a mineral collector, and Enrico Beccuti in 1977. Mine workers at the Balangero
Balangero
Balangero is a comune in the Province of Turin in the Italian region Piedmont, located about 25 km northwest of Turin.Balangero borders the following municipalities: Corio, Coassolo Torinese, Mathi, Lanzo Torinese, and Cafasse....

 mine had first discovered it and named it, based on its overall color and fibrous nature of other minerals present in the mine, Xylotile or Metaxite. This new mineral Balangeroite was tested and found to be completely different from Xylotile and Metaxite in composition as well as optical properties. Turns out that Balangeroite was already discovered and a somewhat pure specimen was in Turin University Mineralogy institute's museum since 1925, inventory no. 14873, labeled as " fibrous serpentine (asbestos)- San Vittore, Balangero".

Literature survey

The most highly cited paper on Balangeroite in the web of science was Robert Compagnoni and colleagues' for " Balangeroite, A new fibrous silicate
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...

 related to Gageite from Balangero, Italy" with twenty five citations. Authors of other articles, most often with Robert Compagnoni as co-author, often cite this article in further research of the mineral and other minerals related to it. Due to its asbestiform
Asbestiform
Asbestiform implies a particular kind of fibrosity in which fibers have high tensile strength and flexibility....

 nature
Nature
Nature, in the broadest sense, is equivalent to the natural world, physical world, or material world. "Nature" refers to the phenomena of the physical world, and also to life in general...

 it has been cited by Francesco Turci (2005) and colleagues in the Journal of toxicology and Environmental Health "Potential Toxicity of no regulated asbestiform minerals: Balangeroite from the Western Alps"

Further investigation

Asbestiform
Asbestiform
Asbestiform implies a particular kind of fibrosity in which fibers have high tensile strength and flexibility....

 minerals are gaining attention in the news and are of great concerns due to the potential health threat their fibers pose when inhaled. Klein and Duttrow chronicle that the regulatory bodies classify asbestiform minerals as having the same effects in both mines as well as in office buildings etc. This has resulted in the banning of Chrysotile
Chrysotile
Chrysotile or white asbestos is the most commonly encountered form of asbestos, accounting for approximately 95% of the asbestos in place in the United States and a similar proportion in other countries. It is a soft, fibrous silicate mineral in the serpentine group of phyllosilicates; as such, it...

 mining
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...

 in the United States due to health concerns of those exposed to asbestos. The intergrowth of Chrysotile
Chrysotile
Chrysotile or white asbestos is the most commonly encountered form of asbestos, accounting for approximately 95% of the asbestos in place in the United States and a similar proportion in other countries. It is a soft, fibrous silicate mineral in the serpentine group of phyllosilicates; as such, it...

 with Balangeroite has become controversial as a result. Tests have been performed by Francesco Turci show that Balangeroite fibers have the ability to produce oxidative stress
Stress (biology)
Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...

, and is therefore a determinant in their genotoxic
Genotoxic
In genetics, genotoxicity describes a deleterious action on a cell's genetic material affecting its integrity. This includes both certain chemical compounds and certain types of radiation....

 effects. Crocidolite's fibers, an 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:...

 riebeckite
Riebeckite
Riebeckite is a sodium-rich member of the amphibole group of silicate minerals, chemical formula [][Na2][32][2|Si8O22]. It forms a series with magnesioriebeckite. It crystallizes in the monoclinic system, usually as long prismatic crystals showing a diamond-shaped cross section, but also in...

, according to Klein and Duttrow pose a greater health hazard especially in pleural abnormalities. The concerns about the toxicity of Balangeroite are especially seen among health organizations within governments. Mineralogists, however, even with concerns about the health hazard Balangeroite might pose, are skeptical about calling it a cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...

- inducing asbestiform
Asbestiform
Asbestiform implies a particular kind of fibrosity in which fibers have high tensile strength and flexibility....

 as various experiments were performed on Balangeroite, show that it cannot be largely responsible for the health effects found in humans.
Balangeroite research has been going on since it was discovered in 1983 but due to its intergrowth with chrysotile
Chrysotile
Chrysotile or white asbestos is the most commonly encountered form of asbestos, accounting for approximately 95% of the asbestos in place in the United States and a similar proportion in other countries. It is a soft, fibrous silicate mineral in the serpentine group of phyllosilicates; as such, it...

, it is very difficult to find a pure sample in large enough quantities for additional testing to get less controversial results. The contaminants in Balangeroite cause it to yield differing results which in turn give rise to controversies as is the case with its potential lethality regarding lung cancer and various pleural abnormalities.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK