Illite, chlorite, montmorillonite and kaolinite, as well as natural marine sediments and mixtures of the standards were subjected to density separation by centrifugation in a linear heavy-liquid gradient. The density layers yielded by centrifugation were recovered and analyzed by X-ray diffraction. Separates were not monomineralic but rather were polymineralic usually with minerals of invarient density, such as quartz, in more than one layer. This incomplete separation is attributed to insufficient centrifugation time. The X-ray character of minerals of variable density changes in such a way as to suggest increased crystallinity with depth in the density gradient. Although several samples were known to contain montmorillonite, none of the density layers showed X-ray evidence of this material. The anomalous behavior of montmorillonite is attributed to its imbibing of the polar organic chemicals used as surfactants into its expandable crystal structure to produce an extremely large basal spacing. This problem can be overcome in some cases by heating the clay to 110°C for 8 hours, but in other cases this had little or no effect in collapsing the expanded structure. Even though the project was not a total success, the method holds promise, providing the duration and intensity of the centrifugation is increased and complete purging of polar organic molecules from expandable layered clays can be accomplished. / Graduation date: 1971

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A study was undertaken to determine some of the chemical and mineralogical characteristics of the Alberni Slay, a Vancouver Island soil which is the representative of the concretionary Brown Group of soils. Chemical analyses showed that iron, silica and aluminum are leached from the profile and though considerable quantities of these elements are precipitated on the surfaces of peds in the deeper horizons of the soil, no horizon of accumulation was formed. The retention of iron in the surface horizon in the form of free iron oxides maintained the percentage of iron in that horizon comparable with the percentage in the C horizon, and resulted in the formation of highly stable concretions in the A-B horizon of the soil. The formation of concretions seemed to have been influenced by the high magnetite content of the soil. The interaction between the positively charged surface of the magnetite particles and organic anion complexes of the cations of the first transitional series impeded the movement of these complexes through the slowly permeable soil and permitted absorption and precipitation to form concretions. The x-ray analyses of the clays revealed a weathering sequence in which chlorite was developed, from weathered primary minerals. The formula for the chlorite separated from the surface horizon clays was calculated and it was found to be a dioctahedral Al-chlorite which had been predicted by Grim and by Brindley, but which had not been previously identified in soils. / Land and Food Systems, Faculty of / Graduate

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Call number: LD2668 .T4 1956 W74 / Master of Science