Abstract
Formation processes of weathering products of pumice collected from a rhyolitic pyroclastic flow deposit were investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). SEM clearly showed the presence of some weathering products adhering to the surface of pumice. XRD showed that the products were composed mainly of noncrystalline materials with a relatively small amount of halloysite (10 Å). TEM and EDX revealed texture transformation sequences from the earliest weathering product to a final product of halloysite as follows: 1) precipitation of very thin flaky or film-like noncrystalline Al-hydroxide; 2) transformation into irregularly aggregated Al-Fe-Si-rich fibrous material; 3) morphological changes to rounded aggregates; 4) development of halloysite-like curled domains with successive decrease in Fe content; and 5) further development of curled domains in rounded aggregates. These materials must be metastable phases at early reaction stages with kinetics limiting formation of the stable equilibrium phase of kaolinite.
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References
Allen BL, Hajek BF. 1989. Mineral occurrence in soil environments. In: Dixon JB, Weed SB, editors. Minerals in soil environments. Wisconsin: Soil Sci Soc Am. p 199–278.
Anovitz LM, Perkins D, Essene EJ. 1991. Metastability in near-surface rocks of minerals in the system Al2O3-SiO2-H2O. Clays Clay Miner 39:39–233.
Aomine S, Wada K. 1962. Differential weathering of volcanic ash and pumice resulting in formation of hydrated halloysite. Am Mineral 47:47–1048.
Aramaki S. 1969. Geology and pyroclastic flow deposits of the Kokubu area, Kagoshima Prefecture. J Geol Soc Jpn 75:425–442.
Banfield JF, Eggleton RA. 1990. Analytical transmission electron microscope studies of plagioclase, muscovite, and K-feldspar weathering. Clays Clay Miner 38:77–89.
Casey WH, Bunker B. 1990. Leaching of minerals and glass surfaces during dissolution. In: Hochella MF Jr, White AF, editors. Rev Mineral 23. Mineral-water interface geochemistry. Washington, DC: Mineral Soc Am. p 397–426.
Chamley H. 1989. Clay formation through weathering. In: Chamley H, editor. Clay sedimentology. New York: Springer, p 21–50.
Dixon JB. 1989. Kaolin and serpentine group minerals. In: Dixon JB, Weed SB, editors. Minerals in soil environments. Wisconsin: Soil Sci Soc Am. p 467–525.
Eggleton RA, Buseck PR. 1980. High resolution electron microscopy of feldspar weathering. Clays Clay Miner 28:28–178.
Elderfield H, Hem JD. 1973. The development of crystalline structure in aluminium hydroxide polymorphs on aging. Mineral Mag 39:39–96.
Fieldes M. 1955. Clay mineralogy of New Zealand soils: II. Allophane and related mineral colloids. New Zealand J Sci Technol B37:336–350.
Hsu PH. 1979. Effect of phosphate and silicate on the crystallization of gibbsite from OH-Al solutions. Soil Sci 127:127–226.
Hsu PH. 1988. Mechanism of gibbsite crystallization from partially neutralized aluminum chloride solution. Clays Clay Miner 36:36–30.
Hsu PH. 1989. Aluminum hydroxides and oxyhydroxides. In: Dixon JB, Weed SB, editors. Minerals in soil environments. Wisconsin: Soil Sci Soc Am. p 331–378.
Hsu PH, Bates TF. 1964. Formation of X-ray amorphous and crystalline hydroxides. Mineral Mag 33:33–768.
Huang WH. 1974. Stabilities of kaolinite and halloysite in relation to weathering of feldspars and nepheline in aqueous solution. Am Mineral 59:59–371.
Luciuk GM, Huang PM. 1974. Effect of monosilicic acid on hydrolytic reactions of aluminum. Soil Sci Soc Am Proc 38:38–244.
Nagasawa K. 1978. Weathering of volcanic ash and other pyroclastic materials. In: Sudo T, Shimoda S, editors. Clays and clay minerals of Japan. Amsterdam: Elsevier. p 105–125.
Sudo T. 1954. Clay mineralogical aspects of the alteration of volcanic glass in Japan. Clay Miner Bull 2:2–106.
Sudo T, Takahashi H. 1956. Shapes of halloysite particles in Japanese clays. Clays Clay Miner 4:4–79.
Tazaki K, Fyfe WS. 1987. Formation of primitive clay precursors on K-feldspar under extreme leaching conditions. In: Schultz LG, van Olphen H, Mumpton FA, editors. Proc Int Clay Conf; 1985; Denver. Bloomington, IN: Clay Miner Soc. p 53–58.
Tazaki K, Fyfe WS, van der Gaast SJ. 1989. Growth of clay minerals in natural and synthetic glasses. Clays Clay Miner 37:37–354.
Tazaki K, Tiba T, Aratani M, Miyachi M. 1992. Structural water in volcanic glass. Clays Clay Miner 40:40–127.
Violante A, Gianfreda L, Violante P. 1993. Effect of prolonged aging on the transformation of short-range ordered aluminum precipitation products formed in the presence of organic and inorganic ligands. Clays Clay Miner 41:41–359.
Violante A, Huang PM. 1993. Formation mechanism of aluminum hydroxide polymorphs. Clays Clay Miner 41:41–597.
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Kawano, M., Tomita, K. & Shinohara, Y. Analytical Electron Microscopic Study of the Noncrystalline Products Formed at Early Weathering Stages of Volcanic Glass. Clays Clay Miner. 45, 440–447 (1997). https://doi.org/10.1346/CCMN.1997.0450313
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DOI: https://doi.org/10.1346/CCMN.1997.0450313