allophane


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allophane

[′a·lə‚fān]
(geology)
Al2O3·SiO2· n H2O A clay mineral composed of hydrated aluminosilicate gel of variable composition; P2O5 may be present in appreciable quantity.
References in periodicals archive ?
The Kimbe soil is an Andisol developed in air-fall tephra consisting of predominantly amorphous material (glass) and plagioclase, with pumice layers and some allophane at depths below 0.
The dominant minerals were smectite (SS), kaolinite (KS), and allophane (AS) in the soils, which were taken, respectively, from the Japanese cities of Isahaya city (32[degrees]50'N, 130[degrees]9'E) in Nagasaki prefecture, and Hukube-cho (35[degrees]3UN, 134[degrees]17'E) and Kotoura-cho (35[degrees]25'N, 133[degrees]39'E) in Tottori prefecture.
allophane, iron oxyhydroxide) in Japanese soils have high adsorption capacity.
Thus, we have the generalized statement of Wall and Hansell (1976:37), for the eastern portion of Nendo that the presence of allophane in these soils suggests that volcanic ash spread over a great part of Santa Cruz and the Reef Islands in the recent past.
1]) was found in the Hapludands (site 3), the clay fraction of which is made up of allophane and imogolite.
Allophane has the unique property of considerable anion exchange capacity.
1]) Soil organic matter (humus) 200 (pH dependent) Vermiculite clay 150 Montmorillion ite clay 100 Smectite 100 Allophane 30 Chlorite 30 Illite clay 30 Micas 30 Kaolinite clay 8-10 Gibbsite (Al mineral) 4 Goethite (Fe mineral) 4 TABLE 20-3 Classifications for Salt-Affected Soils Normal Saline Sodic Soils Soils Soils EC < 4dS [m.
The fact that the soil samples consists mostly of poorly crystalline allophane and /or halloysite clays plus beta quartz with no ma.
The high allophane content of these volcanic deposits makes them particularly prone to landslides, which occur frequently and rejuvenate the soils.
It is likely that the internal parameters of the model would have to be altered to deal with young volcanic soils that contain significant quantities of allophane.
Under high-rainfall or irrigation and well-drained conditions, Si is quickly leached, resulting in low soluble Si concentrations and the formation of allophane (Broquen et al.