Mineralogy and chemistry of some adirondack spodosols
1983
APRIL, RICHARD H. | NEWTON, ROBERT M.
We determined the mineralogy and chemistry of spodosols in three Adirondack lake-watersheds by x-ray and electron microprobe analysis and by optical microscopy. The major minerals present in the soils are quartz, K-feldspar, plagioclase feldspar, and hornblende. Accessory minerals identified with the petrographic microscope include magnetite, ilmenite, hypersthene, garnet, tourmaline, epidote, and zircon. Vermiculite is the dominant clay mineral in the <2-μm fraction. Illite, kaolinite, mixed-layer illite/ vermiculite, smectite, and chlorite are also present, but are less abundant.Vermiculite in the soil profiles contains aluminum interlayer contaminants that prevent the mineral from collapsing to 10 A upon K-saturation. The data suggest that vermiculite in the soil horizons is derived mainly from the weathering of hornblende. The high content of extractable iron in these Adirondack soils (up to 6 wt% Fe) results from the chemical dissolution of iron-rich (ferrohastingsitic) hornblende.
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