Abstract
A Solution containing fluoride (0.4 n NH4F, 0.1 n HCl, n NH4Cl), permits the concentration of dioctahedral mica and dioctahedral vermiculite in mixed clay systems. Allophane, halloysite, kaolinite, and in particular, Mg-rich montmorillonite, biotite, and vermiculite of clay size, are destroyed in 24–48 hr at room temperature. A salt-free, NH4-saturated sample, weighing 80 mg, is shaken in 80 ml of the fluoride solution. The residue is washed with water and X-ray diffraction patterns made.
The method has use in characterizing some of the 2:1 layer silicates in clays. Anatase, if present, is also concentrated and is more positively identified by X-ray diffraction.
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Brown, G. (1953) The dioctahedral analogue of vermiculite: Clay Min. Bull. 2, 64–70.
Black, W. R., and Rich, C. I. (1963, p. 19) Dissolution of soil clay components by acidified ammonium fluoride: Agronomy Abstracts, American Society of Agronomy, 134 pp.
Fife, S V. (1959) An evaluation of ammonium fluoride as a selective extractant for aluminum bound soil phosphate: 1. Preliminary studies on non-soil systems: Soil Sci. 87, 13–21.
Glenn, R. C, and Nash, V. E. (1964) Weathering relationships between gibbsite, kaolinite, chlorite, and expansible layer silicates in selected soils from the lower Mississippi Coastal Plain: Clays and Clay Minerals, Proc. 12th Conf., Pergamon Press, New York, pp. 529–48.
Grim, R. E. (1953) Clay Mineralogy: McGraw-Hill, New York. 384 pp.
Hashimoto, I., and Jackson, M. L. (1960) Rapid dissolution of allophane and kaolinitehalloysite after dehydration: Clays and Clay Minerals, Proc. 7th Conf., Pergamon Press, New York, pp. 102–113.
Hoffman, V., Weiss, A., Koch, G., Mehleb, A., and Scholz, A. (1956) Intercrystalline swelling, cation exchange and anion exchange of minerals of the montmorillonite group and of kaolinite: Clays and Clay Minerals, Proc. 4th Conf., Natl. Acad. Sci.-Natl. Res. Council pub. 456, pp. 273–87.
Huang, P. M., and Jackson, M. L. (1964, p. 19) Mechanism of reaction of neutral fluoride solution with layer silicates and oxides of soils: Agronomy Abstracts, American Society of Agronomy, 126 pp.
Jackson, M. L. (1956) Soil Chemical Analysis—Advanced Course: Published by the Author, Madison, Wis., 991 pp.
Kiely, P. V., and Jackson, M. L. (1964) Selective dissolution of micas from potassium feldspars by sodium pyrosulfate fusion of soils and sediments: Amer. Min. 49, 1648–59.
Kiely, P. V., and Jackson, M. L. (1965) Quartz, feldspar, and mica determination for soils by sodium pyrosulfate fusion, Soil Sci. Soc. Amer. Proc. 29, 159–63.
Macewan, D. M. C (1949) Mineralogical analysis of clays by X-rays: Research 2, 459–66.
Rich, C. I., and Cook, M. G. (1963) Formation of dioctahedral vermiculite in Virginia soils: Clays and Clay Minerals, Proc. 10th Conf., Pergamon Press, New York, pp. 96–106.
Rich, S I., and Obenshain, S. S. (1955) Chemical and clay mineral properties of a Red-Yellow Podzolic Soil derived from muscovite schist: Soil Sci. Soc. Amer. Proc. 19, 334–9.
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Rich, C.I. Concentration of Dioctahedeal Mica and Vermiculite using a Fluoride Solution. Clays Clay Miner. 14, 91–98 (1966). https://doi.org/10.1346/CCMN.1966.0140108
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DOI: https://doi.org/10.1346/CCMN.1966.0140108