Vermiculite

About: Vermiculite is a research topic. Over the lifetime, 2320 publications have been published within this topic receiving 37142 citations.

Influence of climate fluctuation on clay formation in the Baikal drainage basin

Abstract: Sedimentary cores BDP 96 and 98 and VER 96-2 St. 3 from Academician Ridge in Lake Baikal were investigated to investigate the effect of climatic fluctuations on rock weathering and clay formation in the Baikal drainage basin. Illite, smectite, vermiculite, and kaolinite were identified as the major clay minerals in the sediments by X-ray diffraction analysis. Biotite in gravels in alluvial soils of the Baikal drainage area weathers through illite to vermiculite, smectite, and finally to kaolinite. To investigate the relationship between weathering and climate, we measured the clay content and the concentration of biogenic silica in the sediments. High surface productivity (increased biogenic silica) and high chemical weathering (decreased clay content) occurred simultaneously, showing that crustal weathering and soil formation were enhanced under warm climatic conditions.

Mineralogical analysis of soil clays involving vermiculite-chlorite-kaolinite differentiation

Abstract: The content of kaolinite plus halloysite is differentiated quantitatively from chlorite by differential dissolution, even in those samples wherein each mineral has 500°C heat instability of the 7 A peak. This differentiation is possible because the structures of kaolinite and halloysite are destroyed on loss of the 7 A peak, producing amorphous material which is rapidly soluble in 0.5 N NaOH, whereas the chlorite structure remains largely intact with only partial dehydration of the octahedral layer. The amorphous residue of kaolinite-halloysite is dissolved from the other mineral components of the heated sample with sodium hydroxide and the dissolved silica and alumina are allocated to kaolinite. The percentages of kaolinite thus obtained for Elliott, B3–C horizon, 2–0.2 μ fraction, are 3.8 and 3.7 based on silica and alumina, respectively. Similarly, the percentages of kaolinite obtained for Buchanan, B1 horizon, 2-0.2 μ fraction, are 14.9 and 13.8 based on silica and alumina, respectively. Collapse of the vermiculite basal spacing to 10 A on K saturation and heating to 300°C, together with the clear differentiation of kaolinite by differential dissolution analysis (D.D.A.) above, removed the possibility of misinterpretation of the chlorite-like diffractometer tracing by kaolinite and vermiculite occurring together. Other clays, from Davidson and Susquehanna soils, had 44 and 42 to 43 percent kaolinite, based on silica and alumina, respectively. The vermiculite and montmoril-lonite contents of soil clay samples are quantitatively determined by specific surface. The mica percentages are based on the K2O after exclusion of potassium in feldspars. Water loss in the 400°C-to-ignition range gives an important quantitative basis for chlorite.