Palygorskite and Sepiolite

Sepiolite has the ideal formula MggSii203o(OH)4 l2H20 substitution in both tetrahedral and octahedral positions is usually minor, and Mg fills not less than 90% of these positions thus, this material is clearly trioctahedral. Other elements have been sometimes reported in the octahedral centers, such as Fe(II/III), Ni(II), or Mn(II). 

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IMA1 (N.), OTSUKA (R.) and KASHIDE (H.), 1969. Dehydration of palygorskite and sepiolite from the Kuguu District, Tochigi pref. central Japan. Proc. Int. Clay Conf. 1, 99-108. 

Palygorskite and sepiolite are different from other clay minerals in the manner in which the 2 1 layers arc joined Ralher than being joined in a ennlinuous manner, the tetrahedral sheets are joined to an adjacent inverted tetrahedral layer, making the octahedral layers noncontinuous and leaving an open channel in the mineral structure. 

The present-day sediments of the Atlantic do not contain a substantial amount of zeolite (Elderfield, 1976). Clinoptilolite has been found, however, in association with sepiolite, quartz, and mont-morillonite (Hathaway and Sachs, 1965 Bonatti and Joensuu, 1968). The clay minerals palygorskite and sepiolite are usually minor constituents of marine sediments (Hathaway, 1979), and may be detrital (Weaver and Beck, 1977) or authigenic. Their hydrogenous occurrences are usually in basal sediment sections exposed to fluids of elevated temperarnres (Bonatti and Joensuu, 1968 Church and Velde, 1979 see below). 

Palygorskite and sepiolite are magnesium-rich fibrous aluminosilicates that have been identified in basal deep-sea sediments (Table 4 e.g., Hathaway and Sachs, 1965 Bowles et al., 1971 Bonatti and Joensuu, 1968 Church and Velde, 1979 Jones and Galan, 1988 Velde, 1985). These phases are commonly associated with smectite, and it has been suggested that they originate by alteration of montmorillonite by low-temperature, magnesium-rich, hydrothermal solutions (Bonatti and Joensuu, 1968), e.g.. 

The palysepiole polysomatic series PpSs (Ferraris et al. 1998) includes minerals whose structures contain one or both the types of TOT ribbons (modules) which are present in palygorskite and sepiolite these ribbons are reminiscent of the TOT modules occurring in amphiboles (Fig. 19). The two modules are ... 

Palygorskite and sepiolite Authigenic clay minerals (<2pm particle size) in the deep-sea include the fibrous minerals palygorskite and sepiolite and the smectite family of expandable phyllosilicates. Both palygorskite and sepiolite are rare in recent marine... 

The clays found in sedimentary phosphate rocks include illite, kaolinite, smectites, and magnesium-rich clays such as palygorskite and sepiolite. Illite often appears to be a detrital mineral. Kaolinite, smectites, and magnesium-rich clays often appear to occur in zones within phosphate deposits. This zonation may be related to weathering and the general alteration of deposits under surface or near-surface conditions [15,16]. Clay-Iike minerals such as the zeolite clinoptilolite occasionally are found in phosphate rock. 

Li ZH, Wilhns CA, Kniola K (2003) Removal of animiic contaminants using surfactant-modified palygorskite and sepiolite. Clays Clay Miner 51 445-451... 

Palygorskite and sepiolite occurring in soils are generally neoformed under dry or semi-dry climates. These minerals are less stable in wet climates. 

In what natural condition the formation of palygorskite and sepiolite takes place and why ... 

Selective sorption of hydrocarbons by palygorskite and sepiolite Palygorskite/n-heptane + iso-octane Barter et al. (68)... 

Palygorskite and sepiolite are porous microcrystalline solids that have high adsorptive capacity, from which derives multiple industrial applications. Their peculiar crystal structure consists of talclike ribbons parallel to the fiber axis, alter-... 

The adsorption of water from the vapor phase takes place on the exterior surfaces of the clay particles. In addition, for minerals of the group of expanding clays— the montmorillonites including the vermiculties—water is adsorbed between the unit layers. Furthermore, in certain minerals—attapulgite or palygorskite and sepiolites—water adsorption occurs in the channels of molecular dimensions, which are a characteristic of the crystal structure of these minerals. 

The two principal minerals in this group are palygorskite and sepiolite. Little evidence of sepiolite has been observed in soils, but palygorskite occurs widely, particularly in the... 

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