Material

 
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Representative material
The matter how material  represents a particular event determines how it can contribute to an investigation. Any doubt about this point from the beginning reduces the usefulness of the final analysis result. However, if no other material is available, even material with some doubt can be used to set some limits.

Suitable material
Whether the sample material is suited for reconstruction of a time event (in case of a dating analysis) or a local pattern (in case of a tracer study) depends also on the knowledge about the uptake and the fixation of radionuclide in a specific chemical fraction in the sample material. It will be described for the different sorts of materials analyzed.

Samples for 14C analysis
Sizes of carbon containing materials used for analysis. The listed sample sizes correspond to an amount of 1 mg carbon after preparation.

Sort of material

Size [mg] 

Remark

Wood, charcoal

2 - 5 

growth interval

Plants, seeds

2 - 5

one year event

Peat

5 - 10 

contamination by roots (too young) or reservoir age (too old)

Bone

30 - 100

complicated by retention period (growth) and dietary effects (through marine food)

Shells, foraminiphera

30

possible reservoir age

Pottery - food remains

2 - 5 

well-suited

Pottery - matrix

1000

only suited for carbon fractions larger than a few percent 

Mortar - charcoal pieces

2 - 5

mortar can be dated with pieces of charcoal (recognized as such)

Samples for 10Be analysis
Materials used for analysis are sediments, bedrock and meteorites. In sediments
10Be is assumed to be attached to the outer side of the grains. In the preparation process this fraction is separated in a leaching procedure. Sample sizes needed vary from  0.1 gram (deep-sea sediment) to 1 gram of sediment. In bedrock and meteorites the 10Be is in the matrix, and requires total dissolution. The sample size needed is about 0.1 g for meteorites and about 10 g  for bedrock.

Samples for 26Al, 36Cl analysis
Materials used for analysis are bedrock and meteorites. In bedrock and meteorites
10Be is in the matrix, and requires total dissolution. The sample size needed is about 0.1 g for meteorites and about 10 g  for bedrock.