Title: Stability Relationships in Kaolinite, Gibbsite, and Al‐hydroxyinterlayered Vermiculite Soil Systems
Abstract: Abstract The stability of common soil minerals found in Ultisols was studied relative to their natural soil solution composition. The mineralogy of the clay fraction (<2 µm) ranged from 22 to 60% in kaolinite, 0 to 20% in gibbsite, 17 to 57% in hydroxyinterlayered vermiculite (HIV), and 1 to 12% in quartz. Ion activity functions (pH‐⅓pAl and pH 4 SiO 4 ) of soil solutions plotted on a stability diagram along with solubility lines of soil kaolinite, gibbsite, and HIV with the formula K 0.24 Ca 0.08 (Si 3.24 Al 0.76 )(Al 1.56 Fe 0.24 Mg 0.20 )[Al 1.45 (OH) 3.79 ]O 10 (OH) 2 indicated all solutions to be supersaturated with respect to reference kaolinite. Only a few surface soils containing gibbsite had solutions oversaturated relative to gibbsite. Solubility products of HIV were very close to its estimated p k , indicating a near‐equilibrium condition with this mineral, especially in eluviated and transitional subsoil horizons (E and EB). Although the HIV appeared to be metastable relative to reference kaolinite, the data indicated a possible equilibrium coexistence of the two minerals with an HIV stability field below or above that of soil kaolinite, depending on the degree of Al‐hydroxyinterlayering.
Publication Year: 1983
Publication Date: 1983-11-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 73
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