Abstract

The clay fraction from the surface soil of the Alberni soil series was found to consist predominantly of a high Al, dioctahedral chlorite. Its X-ray pattern showed a rather strong, sharp sequence of 14/n Aa basal spacings and an (001) reflection which did not change position and which increased in intensity when the specimen was heated at 550 degrees C. The (hkl) reflections showed close similarities to those of cookeite, a lithium aluminum leptochlorite. Chemical analyses gave 40% SiO 2 , 34% Al 2 O 3 , 4.5% Fe 2 O 3 , 4.5% MgO, and 13% H 2 O. The X-ray results and an Osthaus dissolution curve both resulted in a value of one tetrahedral Al per half cell. Calculation of an approximate structural formula gave (Al (sub 3.2) Fe (sub 0.4) Ti (sub 0.1) Mg (sub 0.8) )(AlSi 3 )O 10 (OH) 8 -(K (sub 0.2) X (sub 0.2) ). The clay fraction of the underlying material consisted of a 40% chlorite-60% montmorillonite, random mixed-layer assemblage. The evidence suggests that the Al chlorite in the surface soil was derived from this type of clay.

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