Palygorskite
Overview
 
Palygorskite or attapulgite is a magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...

 aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 phyllosilicate
Silicate minerals
The silicate minerals make up the largest and most important class of rock-forming minerals, constituting approximately 90 percent of the crust of the Earth. They are classified based on the structure of their silicate group...

 with formula (Mg,Al)2Si
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...

4O
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

10(OH
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

)·4(H2O
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

) which occurs in a type of clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...

 soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...

 common to the Southeastern United States
Southeastern United States
The Southeastern United States, colloquially referred to as the Southeast, is the eastern portion of the Southern United States. It is one of the most populous regions in the United States of America....

. It is one of the types of fuller's earth
Fuller's earth
Fuller's earth is any non-plastic clay or claylike earthy material used to decolorize, filter, and purify animal, mineral, and vegetable oils and greases.-Occurrence and composition:...

.
The name attapulgite is derived from the U.S. town of Attapulgus, Georgia
Attapulgus, Georgia
Attapulgus is a city in Decatur County, Georgia, United States. The population was 492 at the 2000 census.The town's name is an Indian word meaning "Dogwood"; due to the abundance of attapulgite, which makes up the clay soil throughout much of the Southeast, the mineral was named after the...

, in the extreme southwest corner of the state, where the mineral is abundant. It is surface-mined
Surface mining
Surface mining , is a type of mining in which soil and rock overlying the mineral deposit are removed...

 in the area, dry-ground and air-separated into precise particle sizes, and transported in covered hopper
Covered hopper
A Covered Hopper is a railroad freight car. They are designed for carrying dry bulk loads, varying from grain to products such as sand and clay. The cover protects the loads from the weather - dried cement would be very hard to unload if mixed with water in transit, while grain would be liable to...

 cars via the railroad, and is also shipped in 50 pounds (22.7 kg) paper bag
Paper bag
A paper bag or paper sack is a preformed container made of paper, usually with an opening on one side. It can be one layer of paper or multiple layers of paper and other flexible materials. A bag is used for packaging and/or carrying items....

s and bulk bags by truck
Truck
A truck or lorry is a motor vehicle designed to transport cargo. Trucks vary greatly in size, power, and configuration, with the smallest being mechanically similar to an automobile...

.

The name palygorskite is given after the place in the Ural Mountains
Ural Mountains
The Ural Mountains , or simply the Urals, are a mountain range that runs approximately from north to south through western Russia, from the coast of the Arctic Ocean to the Ural River and northwestern Kazakhstan. Their eastern side is usually considered the natural boundary between Europe and Asia...

 where it was discovered.
Palygorskite is known to have been a key constituent of the pigment
Pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...

 called "Maya Blue
Maya Blue
Maya Blue is a unique bright azure blue pigment manufactured by cultures of pre-Columbian Mesoamerica, such as the Maya and Aztec.-Manufacture:...

", which was used notably by the pre-Columbian
Pre-Columbian
The pre-Columbian era incorporates all period subdivisions in the history and prehistory of the Americas before the appearance of significant European influences on the American continents, spanning the time of the original settlement in the Upper Paleolithic period to European colonization during...

 Maya civilization
Maya civilization
The Maya is a Mesoamerican civilization, noted for the only known fully developed written language of the pre-Columbian Americas, as well as for its art, architecture, and mathematical and astronomical systems. Initially established during the Pre-Classic period The Maya is a Mesoamerican...

 of Mesoamerica
Mesoamerica
Mesoamerica is a region and culture area in the Americas, extending approximately from central Mexico to Belize, Guatemala, El Salvador, Honduras, Nicaragua, and Costa Rica, within which a number of pre-Columbian societies flourished before the Spanish colonization of the Americas in the 15th and...

 on ceramics, sculptures, murals and (most probably) Maya textiles.
Encyclopedia
Palygorskite or attapulgite is a magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...

 aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 phyllosilicate
Silicate minerals
The silicate minerals make up the largest and most important class of rock-forming minerals, constituting approximately 90 percent of the crust of the Earth. They are classified based on the structure of their silicate group...

 with formula (Mg,Al)2Si
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...

4O
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

10(OH
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

)·4(H2O
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

) which occurs in a type of clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...

 soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...

 common to the Southeastern United States
Southeastern United States
The Southeastern United States, colloquially referred to as the Southeast, is the eastern portion of the Southern United States. It is one of the most populous regions in the United States of America....

. It is one of the types of fuller's earth
Fuller's earth
Fuller's earth is any non-plastic clay or claylike earthy material used to decolorize, filter, and purify animal, mineral, and vegetable oils and greases.-Occurrence and composition:...

.

Name

The name attapulgite is derived from the U.S. town of Attapulgus, Georgia
Attapulgus, Georgia
Attapulgus is a city in Decatur County, Georgia, United States. The population was 492 at the 2000 census.The town's name is an Indian word meaning "Dogwood"; due to the abundance of attapulgite, which makes up the clay soil throughout much of the Southeast, the mineral was named after the...

, in the extreme southwest corner of the state, where the mineral is abundant. It is surface-mined
Surface mining
Surface mining , is a type of mining in which soil and rock overlying the mineral deposit are removed...

 in the area, dry-ground and air-separated into precise particle sizes, and transported in covered hopper
Covered hopper
A Covered Hopper is a railroad freight car. They are designed for carrying dry bulk loads, varying from grain to products such as sand and clay. The cover protects the loads from the weather - dried cement would be very hard to unload if mixed with water in transit, while grain would be liable to...

 cars via the railroad, and is also shipped in 50 pounds (22.7 kg) paper bag
Paper bag
A paper bag or paper sack is a preformed container made of paper, usually with an opening on one side. It can be one layer of paper or multiple layers of paper and other flexible materials. A bag is used for packaging and/or carrying items....

s and bulk bags by truck
Truck
A truck or lorry is a motor vehicle designed to transport cargo. Trucks vary greatly in size, power, and configuration, with the smallest being mechanically similar to an automobile...

.

The name palygorskite is given after the place in the Ural Mountains
Ural Mountains
The Ural Mountains , or simply the Urals, are a mountain range that runs approximately from north to south through western Russia, from the coast of the Arctic Ocean to the Ural River and northwestern Kazakhstan. Their eastern side is usually considered the natural boundary between Europe and Asia...

 where it was discovered.

Prehistoric use

Palygorskite is known to have been a key constituent of the pigment
Pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...

 called "Maya Blue
Maya Blue
Maya Blue is a unique bright azure blue pigment manufactured by cultures of pre-Columbian Mesoamerica, such as the Maya and Aztec.-Manufacture:...

", which was used notably by the pre-Columbian
Pre-Columbian
The pre-Columbian era incorporates all period subdivisions in the history and prehistory of the Americas before the appearance of significant European influences on the American continents, spanning the time of the original settlement in the Upper Paleolithic period to European colonization during...

 Maya civilization
Maya civilization
The Maya is a Mesoamerican civilization, noted for the only known fully developed written language of the pre-Columbian Americas, as well as for its art, architecture, and mathematical and astronomical systems. Initially established during the Pre-Classic period The Maya is a Mesoamerican...

 of Mesoamerica
Mesoamerica
Mesoamerica is a region and culture area in the Americas, extending approximately from central Mexico to Belize, Guatemala, El Salvador, Honduras, Nicaragua, and Costa Rica, within which a number of pre-Columbian societies flourished before the Spanish colonization of the Americas in the 15th and...

 on ceramics, sculptures, murals and (most probably) Maya textiles. The clay mineral was also used by the Maya as a curative for certain illnesses, and there is evidence to show it was also added to pottery temper. A Maya region source for palygorskite was unknown until the 1960s, when one was found at a cenote
Cenote
A cenote is a deep natural pit, or sinkhole, characteristic of Mexico and Central America, resulting from the collapse of limestone bedrock that exposes groundwater underneath...

on the Yucatán Peninsula
Yucatán Peninsula
The Yucatán Peninsula, in southeastern Mexico, separates the Caribbean Sea from the Gulf of Mexico, with the northern coastline on the Yucatán Channel...

 near the modern township of Sacalum, Yucatán
Yucatán
Yucatán officially Estado Libre y Soberano de Yucatán is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 106 municipalities and its capital city is Mérida....

. A second possible site was more recently (2005) identified, near Ticul
Ticul
Ticul is one of 106 municipalities in Yucatán state, Mexico. It is located in the western part of the state at 100 km south of the state capital city of Mérida. The municipality, which has an area of 355.12 km² , in the 2005 census reported 25,621 inhabitants...

, Yucatán
Yucatán
Yucatán officially Estado Libre y Soberano de Yucatán is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 106 municipalities and its capital city is Mérida....

.

The Maya Blue pigment synthetic was also manufactured in other Mesoamerican regions and used by other Mesoamerican cultures, such as the Aztec
Aztec
The Aztec people were certain ethnic groups of central Mexico, particularly those groups who spoke the Nahuatl language and who dominated large parts of Mesoamerica in the 14th, 15th and 16th centuries, a period referred to as the late post-classic period in Mesoamerican chronology.Aztec is the...

s of central Mexico. The blue coloration seen on Maya
Maya codices
Maya codices are folding books stemming from the pre-Columbian Maya civilization, written in Maya hieroglyphic script on Mesoamerican bark cloth, made from the inner bark of certain trees, the main being the wild fig tree or Amate . Paper, generally known by the Nahuatl word amatl, was named by...

 and Aztec codices
Aztec codices
Aztec codices are books written by pre-Columbian and colonial-era Aztecs. These codices provide some of the best primary sources for Aztec culture....

, and early colonial-era manuscripts and maps, is largely produced by the organic-inorganic mixture of añil
Añil
Indigofera suffruticosa, commonly known as Anil, Guatemalan indigo, Small-leaved indigo , West Indian indigo, and Wild indigo, is a flowering plant in the pea family, Fabaceae...

 leaves and palygorskite, with smaller amounts of other mineral additives. Human sacrificial victims in Postclassic Mesoamerica were frequently daubed with this blue pigmentation.

Extraction

Two companies are involved in the industrial extraction and processing of gellant grade attapulgite clay within the same Attapulgus deposit: Active Minerals International, LLC, and BASF Corp. In 2008, BASF acquired the assets of Zemex Attapulgite leaving only 2 gellant grade producers. Active Minerals operates a dedicated factory to produce the patented product Actigel 208 and built a new state of the art production process in early 2009 involving portable plant processing at the mine site.

Properties

Attapulgite clays are a composite of smectite and palygorskite. Smectites are expanding lattice clays of which bentonite is a commonly known generic name for smectite clays. The palygorskite component is an acicular bristle-like crystalline form which does not swell or expand. Attapulgite forms gel structures in fresh and salt water by establishing a lattice structure of particles connected through hydrogen bonds. Attapulgite, unlike bentonite, will form gel structures in salt water and is used in special salt water drilling mud for drilling formations contaminated with salt. Palygorskite particles can be considered as charged particles with zones of + and - charges. It is the bonding of these alternating charges that allow them to form gel suspensions in salt and fresh water.

Attapulgite clays found in the Meigs-Quincy district are bundles of palygorskite clay particles between 2 and 3 micrometres long and below 3 nanometres in diameter. The bundles are surrounded by a matrix of smectite clays which are slightly swellable. Dry process grades contain up to 25% non-attapulgite material in the form of carbonates and other mineral inclusions. Processing of the clays consist of drying and grinding the crude clay to specific particle size distributions with specific ranges of gel viscosity measured by a variety of means depending on the end use.

Gel grade, dry processed attapulgites are used in a very wide range of applications for suspension, reinforcement and binding properties. Paints, sealants, adhesives, tape-joint compound, catalysts, suspension fertilizers, wild fire suppressants, foundry coatings, animal feed suspensions and molecular sieve binders are just a few uses of dry process attapulgite.

Seven to ten percent attapulgite clay mixed with the eutectic salt, sodium sulfate
Sodium sulfate
Sodium sulfate is the sodium salt of sulfuric acid. When anhydrous, it is a white crystalline solid of formula Na2SO4 known as the mineral thenardite; the decahydrate Na2SO4·10H2O has been known as Glauber's salt or, historically, sal mirabilis since the 17th century. Another solid is the...

 decahydrate (Glaubers salt), will keep anhydrous
Anhydrous
As a general term, a substance is said to be anhydrous if it contains no water. The way of achieving the anhydrous form differs from one substance to another...

 crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...

s suspended in the solution where they will hydrate during phase change and hence contribute to the heat absorbed and released when Glaubers salt are used for heat storage.

Medical use

Attapulgite is used widely in medicine
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

. Taken by mouth, it physically binds to acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...

s and toxic substances in the stomach
Stomach
The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...

 and digestive tract. Also, as an anti-diarrheal, it is believed to work by adsorbing the bacteria or germ that may be causing the diarrhea. For this reason, it has been used in several anti-diarrheal medications, including Diar-Aid, Diarrest, Diasorb, Diatabs, Diatrol, Donnagel, Kaopek, K-Pek, Parepectolin, and Rheaban. It has been used for decades to treat diarrhea.

Until 2003, Kaopectate
Kaopectate
Kaopectate, known medically as bismuth subsalicylate, is an orally taken medication from Chattem, Inc. for the treatment of mild diarrhea. It is also sometimes used to treat indigestion, nausea and stomach ulcers...

 marketed in the US also contained attapulgite. However, at that time, the U.S. Food and Drug Administration
Food and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...

 retroactively rejected medical studies showing its efficacy
Efficacy
Efficacy is the capacity to produce an effect. It has different specific meanings in different fields. In medicine, it is the ability of an intervention or drug to reproduce a desired effect in expert hands and under ideal circumstances.- Healthcare :...

, calling them insufficient. Kaopectate's U.S. formula
Formula
In mathematics, a formula is an entity constructed using the symbols and formation rules of a given logical language....

 was changed to bismuth subsalicylate
Bismuth subsalicylate
Bismuth subsalicylate, with a nominal chemical formula of C7H5BiO4, It is a colloidal substance obtained by hydrolysis of bismuth salicylate . The actual structure is unknown and the formulation is only approximate. Recent evidence indicates that it is composed of a bismuth oxide core structure...

 (pink bismuth). The next year (2004), an additional change in labelling was made; from then on, Kaopectate was no longer recommended for children under 12 years old. Nevertheless, Kaopectate with attapulgite is still available in Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

 and elsewhere. Until the early 1990s, Kaopectate used the similar clay product kaolinite
Kaolinite
Kaolinite is a clay mineral, part of the group of industrial minerals, with the chemical composition Al2Si2O54. It is a layered silicate mineral, with one tetrahedral sheet linked through oxygen atoms to one octahedral sheet of alumina octahedra...

 with pectin
Pectin
Pectin is a structural heteropolysaccharide contained in the primary cell walls of terrestrial plants. It was first isolated and described in 1825 by Henri Braconnot...

(hence the name).

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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