## Sample Preparation

After sieving the samples to obtain the desired grain fraction (90-200 µm for coarse grains, and 4-11 µm for fine grain), the samples are treated with HCl and then with H$$_{2}$$O$$_{2}$$ to remove carbonates and organics.

1. Coarse grain fraction:

To separate quartz- from feldspar- and heavy-minerals a density liquid 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 (90 µm) is necessary to obtain the desired fraction.

1. 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 treatment with H$$_{2}$$SiF$$_{6}$$ is required. This last step can cause a loss of sample material up to 80%.

A sample preparation guideline from created at the University of Bayreuth can be found here.