Talc
A block of talc
General
Category	Minerals
Chemical formula	Mg3Si4O10(OH)2
Identification
Color	white, gray, green or blue
Crystal habit	foliated to fibrous masses
Crystal system	Monoclinic or Triclinic[1]
Cleavage	perfect basal cleavage
Mohs Scale hardness	1
Luster	waxlike or pearly sometimes smooth
Streak	White
Specific gravity	2. A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24 Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the In Chemistry, hydroxide is the most common name for the diatomic Anion OH− consisting of Oxygen and Hydrogen In Mineralogy, shape and size give rise to descriptive terms applied to the typical appearance or habit of Crystals The many terms used by mineralogists A crystal system is a category of Space groups which characterize Symmetry of structures in three dimensions with Translational symmetry in three directions In Crystallography, the monoclinic Crystal system is one of the 7 lattice Point groups A crystal system is described by three vectors. In Crystallography, the triclinic Crystal system is one of the 7 lattice Point groups A crystal system is described by three basis vectors Cleavage, in Mineralogy, is the tendency of crystalline materials to split along definite planes creating smooth surfaces of which there are several named types Cleavage, in Mineralogy, is the tendency of crystalline materials to split along definite planes creating smooth surfaces of which there are several named types 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 Lustre (or 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 an unweathered surface Specific gravity is defined as the ratio of the Density of a given solid or liquid substance to the density of water at a specific temperature and pressure typically 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. Arabic (ar الْعَرَبيّة (informally ar عَرَبيْ) in terms of the number of speakers is the largest living member of the Semitic language A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific Hydrate is a term used in Inorganic chemistry and Organic chemistry to indicate that a substance contains Water. Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24 For the Artificial intelligence Androids of the 1990s Science fiction series Space Above and Beyond, see Silicate (AI Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24 For the Artificial intelligence Androids of the 1990s Science fiction series Space Above and Beyond, see Silicate (AI Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24 Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the In Chemistry, hydroxide is the most common name for the diatomic Anion OH− consisting of Oxygen and Hydrogen In loose form, it is the widely used substance known as talcum powder. Baby powder is an Astringent powder used for preventing rashes on the area covered by a Diaper (see Diaper rash) It occurs as foliated to fibrous masses, its monoclinic crystals being so rare as to be almost unknown. In Crystallography, the monoclinic Crystal system is one of the 7 lattice Point groups A crystal system is described by three vectors. In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating It has a perfect basal cleavage, and the folia are non-elastic, although slightly flexible. Cleavage, in Mineralogy, is the tendency of crystalline materials to split along definite planes creating smooth surfaces of which there are several named types A material is said to be elastic if it deforms under stress (e It is sectile and very soft, with a hardness of 1 (Talc is the softest of the Mohs' scale of mineral hardness, and can be easily scratched by a fingernail). Sectility is the ability to be cut into pieces Metals and paper are sectile. 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 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 It has a specific gravity of 2. Specific gravity is defined as the ratio of the Density of a given solid or liquid substance to the density of water at a specific temperature and pressure typically 5–2. 8, a clear or dusty luster, and is translucent to opaque. Lustre (or luster) is a description of the way light interacts with the surface of a Crystal, rock, or Mineral. Its colour ranges from white to grey or green and it has a distinctly greasy feel. White is a Color, the perception which is evoked by Light that stimulates all three types of color sensitive Cone cells in the Human eye Green is a Color, the perception of which is evoked by light having a spectrum dominated by energy with a Wavelength of roughly 520–570- nm. Its streak is white.

Contents 1 Formation 2 Occurrence 3 Uses 4 Safety 5 See also 6 References

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. Metamorphic rock is the result of the transformation of an existing rock type the protolith, in a process called Metamorphism, which means "change The pyroxenes are a group of important rock-forming Silicate minerals found in many Igneous and metamorphic rocks. Amphibole (pronounced amfi-bowl defines an important group of generally dark-colored rock-forming inosilicate Minerals composed of double chain SiO4 The Mineral olivine (when gem-quality also called Peridot) is a Magnesium Iron silicate with the formula ( Mg This is known as talc carbonation or steatization and produces a suite of rocks known as talc carbonates. 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

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;

Dolomite + Silica + Water → Talc + Calcite + Carbon Dioxide

Talc can also be formed from magnesian chlorite and quartz in blueschist and eclogite metamorphism via the following metamorphic reaction:

Chlorite + Quartz → Kyanite + Talc + H₂O

In this reaction, the ratio of talc and kyanite is dependent on aluminium content with more aluminous rocks favoring production of kyanite. The serpentine group describes a group of common rock-forming hydrous Magnesium Iron phyllosilicate (()3 Minerals they Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Magnesite is not to be confused with Magnetite or Magnemite. Magnesite is Magnesium carbonate, Mg[[carbon Water is a common Chemical substance that is essential for the survival of all known forms of Life. Skarn is a Metamorphic rock that is usually variably colored green or red occasionally grey black brown or white Dolomite (ˈdɒləmaɪt is the name of a Sedimentary Carbonate rock and a Mineral, both composed The Chemical compound silicon dioxide, also known as silica or silox (from the Latin " Silex " is an Oxide Calcite is a carbonate mineral and the most stable polymorph of Calcium carbonate ( Ca[[carbon C]] O 3 Blueschist (ˈbluːʃɪst is a rock that forms by the Metamorphism of Basalt and rocks with similar composition at high Pressures and low Eclogite (ˈɛklədʒaɪt is a coarse-grained Mafic ( Basaltic in composition Metamorphic rock. A metamorphic reaction is a Chemical reaction that takes place during the Geological process of Metamorphism in an amalgamate of Minerals that The chlorites are a group of phyllosilicate Minerals Chlorites can be described by the following four endmembers based on their chemistry via substitution Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in Kyanite, whose name derives from the Greek word kyanos, meaning blue is a typically blue Silicate Mineral, commonly found in Aluminium -rich WikipediaNaming This is typically associated with high-pressure, low-temperature minerals such as phengite, garnet, glaucophane within the lower blueschist facies. Fengite is a transparent form of Marble or Alabaster. In former times it was sometimes used for windows instead of glass The garnet group includes a group of minerals that have been used since the Bronze Age as gemstones and abrasives Glaucophane is a Mineral belonging to the Amphibole group chemical formula Na 2( Mg, Fe)3 Al 2 Blueschist (ˈbluːʃɪst is a rock that forms by the Metamorphism of Basalt and rocks with similar composition at high Pressures and low Such rocks are typically white, friable, and fibrous, and are known as whiteschist.

Talc is a tri-octahedral layered mineral; its structure is similar to that of pyrophyllite, but with magnesium in the octahedral sites of the composite layers. Pyrophyllite is a phyllosilicate Mineral species belonging to the Clay family and composed of Aluminium Silicate Hydroxide Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24 ^[1]

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. Ultramafic (also referred to as ultrabasic) rocks are igneous and meta -igneous rocks with very low Silica content (less than 45% generally Soapstone (also known as steatite or soaprock) is a Metamorphic rock, a talc- Schist. Blueschist (ˈbluːʃɪst is a rock that forms by the Metamorphism of Basalt and rocks with similar composition at high Pressures and low 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. The United States of America —commonly referred to as the 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 natural Mountain building and may be studied as a tectonic structural event as a geographical event and

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 is a geologic term for a suite of rock and mineral compositions found in metamorphic Ultramafic rocks A craton ( Greek kratos / κρἀτος ( neut. "strength" is an old and stable part of the Continental crust that has survived Komatiites are Ultramafic mantle-derived Volcanic rocks They have low SiO2 low K2O low Al2O3 and high to extremely high The Yilgarn Craton is a large Craton which constitutes the bulk of the Western Australian land mass Western Australia is a state occupying the entire western third of the Australian continent. Talc-carbonate ultramafics are also known from the Lachlan Fold Belt, eastern Australia, from Brazil, the Guiana Shield, and from the ophiolite belts of Turkey, Oman and the Middle East. The Lachlan Fold Belt ( LFB) or Lachlan Orogen is a geological subdivision of the east part of Australia. For a topic outline on this subject see List of basic Australia topics. |utc_offset = -2 to -4 |time_zone_DST = BRST |utc_offset_DST = -2 to -5 |cctld The Guiana Shield (Guayana is one of the three Cratons of the South American Plate. An Ophiolite is a section of the Earth's Oceanic crust and the underlying upper mantle that has been uplifted or emplaced to be exposed within Continental Turkey (Türkiye known officially as the Republic of Turkey ( is a Eurasian Country that stretches Oman, officially the Sultanate of Oman ( Arabic: سلطنة عُمان) is an Arab Country in Southwest Asia on the southeast The Middle East is a Subcontinent with no clear boundaries often used as a synonym to Near East, in opposition to Far East.

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

Uses

A coarse grayish-green high-talc rock is soapstone or steatite and has been used for stoves, sinks, electrical switchboards, etc. Soapstone (also known as steatite or soaprock) is a Metamorphic rock, a talc- Schist. Talc finds use as a cosmetic (talcum powder), as a lubricant, and as a filler in paper manufacture. A lubricant (sometimes referred to as a "Lube" is a substance (often a liquid introduced between two moving surfaces to reduce the Friction between them improving Paper is thin material mainly used for writing upon printing upon or packaging Talc is used in baby powder, an astringent powder used for preventing rashes on the area covered by a diaper (see diaper rash). Baby powder is an Astringent powder used for preventing rashes on the area covered by a Diaper (see Diaper rash) An astringent (also spelled adstringent) substance is a chemical that tends to shrink or constrict Body tissues usually locally after Topical medicinal "Nappy" redirects here For other uses see Nappy (disambiguation and Diaper (disambiguation. Diaper rash ( US) or nappy rash ( UK) is a generic term applied to Skin rashes in the Diaper area that are caused by various skin Most tailor's chalk is talc, as is the chalk often used for welding or metalworking. Chalk (ʧɔːk is a soft white porous Sedimentary rock, a form of Limestone composed of the Mineral Calcite. Welding is a fabrication process that joins materials usually Metals or Thermoplastics by causing coalescence. Metalworking is craft and practice of working with Metals to create individual parts assemblies or large scale structures

Talc is also used as food additive or in pharmaceutical products. Food additives are substances added to food to preserve flavour or improve its taste and appearance In medicine talc is used as a pleurodesis agent to prevent recurrent pneumothorax. Pleurodesis is the artificial obliteration of the pleural space. In the European Union the additive number is E553b. The European Union ( EU) is a political and economic union of twenty-seven member states, located primarily in

Safety

Several studies have established preliminary links between talc and pulmonary issues,^[2] lung cancer,^[3][4] skin cancer and ovarian cancer. lung is the essential Respiration organ in air-breathing Animals including most Tetrapods a few Fish and a few Snails The most primitive Lung cancer is a Disease of uncontrolled Cell growth in tissues of the Lung. Skin cancer is a Malignant growth on the Skin which can have many causes Ovarian cancer is a cancerous growth arising from an Ovary. The cancer most commonly forms in the lining of the ovary (resulting in epithelial ^[5] This is a major concern considering talc's widespread commercial and household use. 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. ^[3] 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. ^[6] However, 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. The term carcinogen refers to any substance Radionuclide or radiation that is an agent directly involved in the promotion of Cancer or in the fatation of its propagation Asbestos is a group of Minerals with long thin fibrous Crystals The word "asbestos" (῾ἀσβεστος is derived from a Greek adjective Amphibole (pronounced amfi-bowl defines an important group of generally dark-colored rock-forming inosilicate Minerals composed of double chain SiO4 Generally Recognized as Safe ( GRAS) is a United States of America Food and Drug Administration (FDA designation that a chemical or substance added to food ^[7]

See also

• List of minerals
• Serpentinite
• Talc carbonate
• Magnesite
• Blueschist
• Metamorphic rocks
• Asbestos
• French chalk

References

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

1. ^ ^{a b} An Introduction to the Rock-Forming Minerals, second edition, by W. This is a List of Minerals for which there are Wikipedia articles Serpentinite is a rock composed of one or more Serpentine Minerals Minerals in this group are formed by serpentinization a hydration and metamorphic Talc carbonate is a geologic term for a suite of rock and mineral compositions found in metamorphic Ultramafic rocks Magnesite is not to be confused with Magnetite or Magnemite. Magnesite is Magnesium carbonate, Mg[[carbon Blueschist (ˈbluːʃɪst is a rock that forms by the Metamorphism of Basalt and rocks with similar composition at high Pressures and low Metamorphic rock is the result of the transformation of an existing rock type the protolith, in a process called Metamorphism, which means "change Asbestos is a group of Minerals with long thin fibrous Crystals The word "asbestos" (῾ἀσβεστος is derived from a Greek adjective French chalk is a type of Talc used by tailors for marking Cloth, by cleaners for removing grease from cloth and as a dry Lubricant in its powdered A. Deer, R. A. Howie, and J. Zussman, 1992, Prentice Hall, ISBN 0-582-30094-0.
2. ^ Hollinger (1990). "Pulmonary toxicity of inhaled and intravenous talc.".  
3. ^ ^{a b} National Toxicology Program (1993). "NTP Toxicology and Carcinogenesis Studies of Talc (Non-Asbestiform) in Rats and Mice (Inhalation Studies).".  
4. ^ NIOSH Worker Notification Program. "Health effects of mining and milling talc.".  (historical)
5. ^ Harlow, Cramer, Bell, et al. (1992). "Perineal exposure to talc and ovarian cancer risk.".  
6. ^ Henderson WJ, Joslin CA, Turnbull AC, Griffiths K (1971). "Talc and carcinoma of the ovary and cervix.". J Obstet Gynaecol Br Commonw 78 (3): 266-272.  
7. ^ CFSAN/Office of Food Additive Safety (July 2006). Food Additive Status List. U. S. Food and Drug Administration. Retrieved on December 2007. December 2007 is the twelfth month of that year It began on a Saturday and 31 days later ended on a Monday

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