Talc
A block of talc
General
Category	Mineral
Chemical formula	Mg3Si4O10(OH)2
Identification
Color	white to gray or green
Crystal habit	foliated to fibrous masses
Crystal system	Monoclinic
Cleavage	perfect basal cleavage
Mohs Scale hardness	1
Luster	waxlike or pearly
Streak	White
Specific gravity	2.5-2.8

Talc (derived from the Persian via Arabic talq) is a mineral composed of hydrated magnesium silicate with the chemical formula H₂Mg₃(SiO₃)₄ or Mg₃Si₄O₁₀(OH)₂. It occurs as foliated to fibrous masses, its monoclinic crystals being so rare as to be almost unknown. It has a perfect basal cleavage, and the folia are non-elastic, although slightly flexible. It is sectile and very soft, with a hardness of 1 (Talc is the softest of the Mohs' scale of mineral hardness). It has a specific gravity of 2.5–2.8, a clear or dusty luster, and is translucent to opaque. Its colour ranges from white to gray or green and it has a distinctly greasy feel. Its streak is white. Image File history File links Talc_block. ... Minerals are natural compounds formed through geological processes. ... This article does not cite its references or sources. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white Standard atomic weight 24. ... It has been suggested that Silicons ranking be merged into this article or section. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... Hydroxide is a polyatomic ion consisting of oxygen and hydrogen: OH− It has a charge of −1. ... In mineralogy, shape and size give rise to descriptive terms applied to the typical appearance, or habit of crystals. ... A crystal system is a category of space groups, which characterize symmetry of structures in three dimensions with translational symmetry in three directions, having a discrete symmetry group. ... In crystallography, the monoclinic crystal system is one of the 7 lattice point groups. ... Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types: Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes. ... Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types: Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes. ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock or mineral. ... The streak (also called powder color) of a mineral is the color of the powder produced when it is dragged across a unweathered surface. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... Persian (Local names: فارسی Fârsi or پارسی Pârsi)* is an Indo-European language spoken in Iran, Afghanistan and Tajikistan as well as by minorities in Uzbekistan, Turkmenistan, India, Pakistan, Azerbaijan, Georgia, Southern Russia, neighboring countries, and elsewhere. ... Arabic ( or just ) is the largest living member of the Semitic language family in terms of speakers. ... Minerals are natural compounds formed through geological processes. ... Hydrate is a term which means different things in inorganic chemistry and organic chemistry. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white Standard atomic weight 24. ... In chemistry, a silicate is a compound containing an anion in which one or more central silicon atoms are surrounded by electronegative ligands. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white Standard atomic weight 24. ... In chemistry, a silicate is a compound containing an anion in which one or more central silicon atoms are surrounded by electronegative ligands. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white Standard atomic weight 24. ... It has been suggested that Silicons ranking be merged into this article or section. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... Hydroxide is a polyatomic ion consisting of oxygen and hydrogen: OH− It has a charge of −1. ... In crystallography, the monoclinic crystal system is one of the 7 lattice point groups. ... Quartz crystal Synthetic bismuth crystal Insulin crystals Gallium, a metal that easily forms large single crystals A huge monocrystal of potassium dihydrogen phosphate grown from solution by Saint-Gobain for the megajoule laser of CEA. In chemistry and mineralogy, a crystal is a solid in which the constituent atoms, molecules... Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types: Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes. ... Elasticity is a branch of physics which studies the properties of elastic materials. ... Look up Sectility on Wiktionary, the free dictionary Sectility is the ability to be cut into pieces. ... The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... For the file system called Lustre, see Lustre (file system) Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock or mineral. ... This article is about the color. ... Gray or grey is a color seen commonly in nature. ... Mossy, green fountain in Wattens, Austria. ...

Formation

Talc is a metamorphic mineral resulting from the metamorphism of magnesian minerals such as pyroxene, amphibole, olivine and other similar minerals in the presence of carbon dioxide and water. This is known as talc carbonation or steatization and produces a suite of rocks known as talc carbonates. Quartzite, a form of metamorphic rock, from the Museum of Geology at University of Tartu collection. ... Figure 1:Mantle-peridotite xenolith with green peridot olivine and black pyroxene crystals from San Carlos Indian Reservation, Gila Co. ... For the logical fallacy, see Amphibology. ... The mineral olivine (also called chrysolite and, when gem-quality, peridot) is a magnesium iron silicate with the formula (Mg,Fe)2SiO4. ... Talc carbonate is a geologic term for a suite of rock and mineral compositions found in metamorphic ultramafic rocks. ...

Talc is primarily formed via hydration and carbonation of serpentine, via the following reaction;

Serpentine + Carbon Dioxide → Talc + Magnesite + Water Serpentine Serpentine is a group of common rock-forming hydrous magnesium iron phyllosilicate ((Mg, Fe)3Si2O5(OH)4) minerals; it may contain minor amounts of other elements including chromium, manganese, cobalt and nickel. ... Carbon dioxide is a chemical compound composed of one carbon and two oxygen atoms. ... Magnesite is magnesium carbonate, MgCO3. ... Impact of a drop of water creating circular capillary waves. ...

Talc can also be formed via a reaction between dolomite and silica, which is typical of skarnification of dolomites via silica-flooding in contact metamorphic aureoles; Skarn is a fine grained metamorphic rock that is usually variably colored green or red, occasionally grey, black, brown or white. ...

Dolomite + Silica + Water → Talc + Calcite + Carbon Dioxide Dolomite crystals from Touissite, Morocco Dolomite is the name of both a carbonate rock and a mineral consisting of calcium magnesium carbonate (formula: CaMg(CO3)2) found in crystals. ... The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ... Doubly refracting Calcite from Iceberg claim, Dixon, New Mexico. ...

Talc can also be formed from magnesian chlorite and quartz in blueschist and eclogite metamorphism via the following reaction: Blueschist is a rock that forms by the metamorphism of sodium-rich basic rocks at high pressures and low temperatures, approximately corresponding to a depth of 15 to 30 kilometers and 200 to 400 degrees Celsius (cool by metamorphic standards). ... Eclogite is a coarse-grained, mafic-to-ultramafic grouping of metamorphic rocks of special interest on account of the variety of minerals they contain and their microscopic structures and geological relationships. ...

Chlorite + Quartz → Kyanite + Talc + H₂O The chlorite ion This discusses some chlorine compounds. ... Quartz is one of the most common minerals in the Earths continental crust. ... Kyanite, whose name derives from the Greek, kyanos, meaning blue, is a typically blue silicate mineral, commonly found in aluminium-rich metamorphic pegmatites and/or sedimentary rock. ...

In this reaction, the ratio of talc and kyanite is dependent on aluminium content with more aluminous rocks favoring production of kyanite. This is typically associated with high-pressure, low-temperature minerals such as phengite, garnet, glaucophane within the lower blueschist facies. Such rocks are typically white, friable, and fibrous, and are known as whiteschist. General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13, 3, p Appearance silvery Standard atomic weight 26. ... Fengite is a transparent form of marble or alabaster. ... Garnet is a group of minerals that have been used since the Bronze Age as gemstones and abrasives. ... Glaucophane Glaucophane is a mineral belonging to the amphibole group, chemical formula Na2(Mg,Fe)3Al2Si8O22(OH)2. ... Blueschist is a rock that forms by the metamorphism of sodium-rich basic rocks at high pressures and low temperatures, approximately corresponding to a depth of 15 to 30 kilometers and 200 to 400 degrees Celsius (cool by metamorphic standards). ...

Occurrence

Talc is a very common metamorphic mineral in metamorphic belts which contain ultramafic rocks, such as soapstone (a high-talc rock), and within whiteschist and blueschist metamorphic terranes. Prime examples of whiteschists include the Franciscan Metamorphic Belt of the western United States, the western European Alps especially in Italy, certain areas of the Musgrave Block, and some collisional orogens such as the Himalayas. Igneous rock which crystallizes from silicate minerals at the highest temperatures is referred to as ultramafic rock. ... The lid of a soapstone box to show the characteristic look of the stone. ... Blueschist is a rock that forms by the metamorphism of sodium-rich basic rocks at high pressures and low temperatures, approximately corresponding to a depth of 15 to 30 kilometers and 200 to 400 degrees Celsius (cool by metamorphic standards). ... The west face of the Petit Dru above the Chamonix valley near the Mer de Glace. ... The Musgrave Block is an east-west trending belt of Proterozoic granulite-gneiss basement rocks approximately 500km long. ... // Orogeny (Greek for mountain generating) is the process of mountain building, and may be studied as a tectonic structural event, as a geographical event and a chronological event, in that orogenic events cause distinctive structural phenomena and related tectonic activity, affect certain regions of rocks and crust and happen within... Perspective view of the Himalayas and Mount Everest as seen from space looking south-south-east from over the Tibetan Plateau. ...

Talc carbonated ultramafics are typical of many areas of the Archaean cratons, notably the komatiite belts of the Yilgarn Craton in Western Australia. Talc-carbonate ultramafics are also known from the Lachlan Fold Belt, eastern Australia, from Brazil, the Guyana Shield, and from the ophiolite belts of Turkey, Oman and the Middle East. Talc carbonate is a geologic term for a suite of rock and mineral compositions found in metamorphic ultramafic rocks. ... The Archean is a geologic eon; it is a somewhat antiquated term for the time span between 2500 million years before the present and 3800 million years before the present. ... World geologic provinces. ... Komatiites are ultramafic mantle-derived volcanic rocks. ... // The Yilgarn Craton is a huge craton which constitutes the bulk of the Western Australian land mass. ... Capital Perth Government Constitutional monarchy Governor Ken Michael Premier Alan Carpenter (ALP) Federal representation  - House seats 15  - Senate seats 12 Gross State Product (2004-05)  - Product ($m)  $100,900 (4th)  - Product per capita  $50,355/person (3rd) Population (December 2006)  - Population  2,050,900 (4th)  - Density  0. ... Basic geological regions of Australia, by age. ... Mt Roraima in Guyana The Guiana Shield (Spanish: Guayana) forms a portion of the northern coast of South America. ... Ophiolites are sections of oceanic lithosphere that have been uplifted or emplaced to be exposed within continental crustal rocks. ... A map showing countries commonly considered to be part of the Middle East The Middle East is a region comprising the lands around the southern and eastern parts of the Mediterranean Sea, a territory that extends from the eastern Mediterranean Sea to the Persian Gulf. ...

Notable economic talc occurrences include the Mount Seabrook talc mine, Western Australia, formed upon a polydeformed, layered ultramafic intrusion.

Uses

Talcum Powder

A coarse grayish-green high-talc rock is soapstone or steatite and has been used for stoves, sinks, electrical switchboards, etc. Talc finds use as a cosmetic (talcum powder), as a lubricant, and as a filler in paper manufacture. Talc is used in baby powder, an astringent powder used for preventing rashes on the area covered by a diaper (see diaper rash). Most tailor's chalk is talc, as is the chalk often used for welding or metalworking. Image File history File linksMetadata Download high resolution version (3072x2304, 2236 KB) Summary Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Talc Talk:Talc User:Mattman723/photos Metadata This file contains additional information, probably added from the... Image File history File linksMetadata Download high resolution version (3072x2304, 2236 KB) Summary Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Talc Talk:Talc User:Mattman723/photos Metadata This file contains additional information, probably added from the... The lid of a soapstone box to show the characteristic look of the stone. ... For other uses, see Cosmetic. ... A lubricant (colloquially, lube, although this may also refer to personal lubricants) is a substance (usually a liquid) introduced between two moving surfaces to reduce the friction and wear between them. ... A blank sheet of paper Paper is a commodity of thin material produced by the amalgamation of fibers, typically vegetable fibers composed of cellulose, which are subsequently held together by hydrogen bonding. ... Talc block Talc is a mineral composed of hydrated magnesium silicate with the chemical formula H2Mg3(SiO3)4 or Mg3Si4O10(OH)2. ... An astringent substance is a chemical substance that tends to shrink or constrict body tissues, usually locally after topical medicinal application. ... This article does not cite its references or sources. ... Diaper rash (US) or nappy rash (UK), is a generic term applied to rashes seen in the diaper area that may be caused by a variety of skin disorders. ... The Needles,situated on the Isle Of Wight, are part of the extensive Southern England Chalk Formation. ... Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. ... This article or section is in need of attention from an expert on the subject. ...

Talc is also used as food additive or in pharmaceutical products. In medicine talc is used as a pleurodesis agent to prevent recurrent pneumothorax. In the European Community the additive number is E553b. Food additives are substances added to food to preserve flavour or improve its taste and appearance. ... The European Community (EC), most important of two European Communities, was originally founded on March 25, 1957 by the signing of the Treaty of Rome under the name of European Economic Community. ...

Safety

Several studies have established preliminary links between talc and pulmonary issues,^[1] lung cancer,^[2][3] skin cancer and ovarian cancer.^[4] This is a major concern considering talc's widespread commercial and household use. However, no conclusive study has yet been made to determine either the toxicity and/or carcinogenic nature of talc and the long history of safe use suggests that these concerns are unfounded. The U.S. Food and Drug Administration (FDA) considers non-asbestiform talc, that is talc which does not contain potentially carcinogenic asbestiform amphibole fibers, to be Generally recognized as safe (GRAS) for use in cosmetics. In 1993, a US National Toxicology Program report found that cosmetic grade talc caused tumours in animals, even though it contained no asbestos-like fibres. Scientists have been aware of the toxicity of talc since the late 1960s, and in 1971 researchers found particles of talc embedded in 75 percent of the ovarian tumors studied. The heart and lungs (from an older edition of Grays Anatomy) The lung is an organ belonging to the respiratory system and interfacing to the circulatory system of air-breathing vertebrates. ... Lung cancer is a transformation and expansion of lung tissue, and is the most lethal of all cancers worldwide, responsible for 1. ... Skin cancer is a malignant growth on the skin, which can have many causes. ... Ovarian cancer is a malignant ovarian neoplasm (an abnormal growth located on the ovaries). ... The Food and Drug Administration (FDA) is an agency of the United States Department of Health and Human Services and is responsible for regulating food (humans and animal), dietary supplements, drugs (human and animal), cosmetics, medical devices (human and animal) and radiation emitting devices (including non-medical devices), biologics, and... The term carcinogen refers to any substance, radionuclide or radiation which is an agent directly involved in the promotion of cancer or in the facilitation of its propagation. ... Fibrous asbestos on muscovite Asbestos Asbestos Asbestos (a misapplication of Latin: asbestos quicklime from Greek : a, not and sbestos, extinguishable) describes any of a group of minerals that can be fibrous, many of which are metamorphic and are hydrous magnesium silicates. ... For the logical fallacy, see Amphibology. ... Generally Recognized as Safe (GRAS) is an FDA designation that a chemical or substance (including certain pesticides) added to food is considered safe by experts, and so is exempted from the usual FFDCA food additive tolerance requirements. ...

See also

Wikimedia Commons has media related to:

Talc

• List of minerals
• Serpentinite
• Talc carbonate
• Magnesite
• Blueschist
• Metamorphic rocks
• Asbestos
• Links to external chemical sources

Image File history File links Commons-logo. ... Wikimedia Commons logo by Reid Beels The Wikimedia Commons (also called Commons or Wikicommons) is a repository of free content images, sound and other multimedia files. ... Gem animals. ... A sample of serpentinite rock, partially made up of chrysotile Serpentinite is a rock comprised of one or more serpentine minerals. ... Talc carbonate is a geologic term for a suite of rock and mineral compositions found in metamorphic ultramafic rocks. ... Magnesite is magnesium carbonate, MgCO3. ... Blueschist is a rock that forms by the metamorphism of sodium-rich basic rocks at high pressures and low temperatures, approximately corresponding to a depth of 15 to 30 kilometers and 200 to 400 degrees Celsius (cool by metamorphic standards). ... Metamorphic rock is the result of the transformation of a pre-existing rock type, the protolith, in a process called metamorphism, which means change in form, derived from the Greek words meta, change, and morphe, form. The protolith is subjected to extreme heat (>150 degrees Celsius) and pressure causing profound... Fibrous asbestos on muscovite Asbestos Asbestos Asbestos (a misapplication of Latin: asbestos quicklime from Greek : a, not and sbestos, extinguishable) describes any of a group of minerals that can be fibrous, many of which are metamorphic and are hydrous magnesium silicates. ...

References

• mineral.galleries.com
• webmineral.com
• www.mindat.org

1. ^ Hollinger (1990). "Pulmonary toxicity of inhaled and intravenous talc.". 
2. ^ National Toxicology Program (1993). "NTP Toxicology and Carcinogenesis Studies of Talc (Non-Asbestiform) in Rats and Mice (Inhalation Studies).". 
3. ^ NIOSH Worker Notification Program. "Health effects of mining and milling talc.". (historical)
4. ^ Harlow, Cramer, Bell, et al. (1992). "Perineal exposure to talc and ovarian cancer risk.".