Hexafluorosilicic Acid Reagent Modification for Quartz Isolation
1976
Jackson, M. L. | Sayin, Mahmut | Clayton, R. N.
Up to three sequential 3-day treatments with commercial H₂SiF₆ were required to remove feldspar XRD peaks from many samples of loess and glacial till. Two such repeated treatments lowered the yield of isolated quartz by about 10%. For example, with Memphis C horizon loess from Yalobusha Co., Miss., the yield dropped from 29 to 19% of the 1–10 µm size fraction. Pretreatment of the H₂SiF₆ with finely ground quartz (1–100 µm size fraction) raised the quartz yield after one or two 3-day treatments about 10%, for example from 29 to 39% of the initial 1–10 µm fraction of Yalobusha loess. After a third 3-day treatment the yield was 32%. The quartz of this loess was of 100% purity after one 3-day H₂SiF₆ treatment, as established by XRD and XRS. The oxygen isotope delta value was affected a little, the δ¹⁸O declining from 17 to 16‰ for the 1–10 µm quartz isolates treated one to three times with H₂ SiF₆, and fine quartz particles were released (SEM) from clusters in fine chert contained in the loess.
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