Sample Preparation

After sieving the samples to obtain the desired grainfraction (90 - 200 µm for coarse grains, and 4 - 11 µm for finegrain), the samples are treated with HCl and then with H2O2 to remove carbonates and organics.

a) Coarse grain fraction:
To separate quartz- from feldspar- and heavy-minerals a densityliquid is used. The so gained quartz-fraction is treated with HF to remove the outer shell with a thickness of ca. 20 µm. Then you can disregard the alpha-radiation. A last mesh minus (90µm) is necessary to obtain the desired fraction.

b) Fine grain fraction:
To get the 4 - 11 µm fraction Stokes Law is used (various settling rates for different grain sizes). The result is a polymineral-sample. For a pure quartz-fraction a tratment with H2SiF6 is required. This last step can cause a loss of sample material up to 80%.


Click Downloads and look for Miscellaneous for further information.