A. F. Frederickson

Bio: A. F. Frederickson is an academic researcher from Washington University in St. Louis. The author has contributed to research in topics: Solubility & Hydrothermal circulation. The author has an hindex of 5, co-authored 6 publications receiving 48 citations.

New work on petrofabrics

Abstract: Recent work on petrofabrics, particularly work written in German, is reviewed in the light of the author's own experience. Topics discussed include quantitative comparison of fabric diagrams, the thermodynamics of crystal growth under stress, interpretation of grain boundaries, comparison of fabrics of metal and silicate crystal aggregates, recrystallisation fabrics, quantitative evaluation of rock deformation using parameters of ooliths, fossils and folds, and structural sequence in orogenic zones.

Silica in Soils1

Abstract: Publisher Summary Silica in free and combined forms is a dominant component of the solid material of many soils, and dissolved silica is commonly a major solute of soil solutions. Breakdown of primary silicates, translocation of silica in solution, and deposition of secondary silica-containing substances are involved in the development of soils. Ions essential for the growth of plants are released to the soil solution as silicates weather, and these ions may be held against leaching at exchange sites on other silicates. Silica is absorbed in appreciable quantities by some plants and is returned to the surface of the soil as the plants decay. The nature and transformations of silica and silicates in soil are, thus, fundamental to an understanding of many aspects of soil and plant sciences.

The hydrothermal synthesis of low albite

Abstract: Glasses on the join NaAlSi3O8-Na2Si2O5 were devitrified hydrothermally at pressures of 1 to 10 kb and at temperatures in the range 200 to 700° C to define more adequately the physical and chemical environments which favor crystallization of the fully ordered polymorph of albite. The presence of Na2Si2O5 allows the synthesis of low albite with an obliquity of 1.140° (Cu Kα radiation) in runs of relatively short duration. The effect of increasing total pressure and time, and of decreasing temperature and amount of water down to critical values, is to favor the synthesis of ordered albite. Excess sodium is the chemical constituent necessary for ordering to proceed at a relatively rapid rate; this rate seems to vary with the ratio aNa+/aH+, and hence with the peralkalinity of the aqueous fluid attending recrystallization. The chemical environment of recrystallization thus seems as important as temperature in determining the ultimate degree of Si-Al order attained in albite.