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Silica in Duric Soils: II. Mineralogy
Author(s) -
Chadwick O. A.,
Hendricks D. M.,
Nettleton W. D.
Publication year - 1987
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1987.03615995005100040029x
Subject(s) - pedogenesis , soil water , mineralogy , precipitation , geology , microcrystalline , quartz , clay minerals , dissolved silica , goethite , volcanic ash , geochemistry , volcano , adsorption , chemistry , dissolution , soil science , paleontology , physics , organic chemistry , meteorology
Opal‐A and opal‐CT were identified by x‐ray diffraction as the primary pedogenic silica minerals in two central Nevada duric soils. Opal‐A was also present in the form of allogenic volcanic glass. Pedogenic microcrystalline quartz was not identified. Saturated paste extracts contained > 60 mg L −1 Si(OH) 4 and opal‐A precipitation is likely during soil dehydration. Opal‐CT precipitates from soil solution once silica concentrations have been reduced through adsorption, precipitation, and/or increased solution ionic strength, or it may be produced by transformation from opal‐A by mineral aging processes. High concentrations of silica in soil solution favor opal formation in preference to deposition of microcrystalline quartz.