I wouldn't doubt granite being used for hammerstones. But: would
they have been used if silt-like sandstones were available.
In the Netherlands all bedrock is scarce to non existing so I wonder
to what extend people accept pour material. If it is really available
you might expect even poor grade stuff to be used. Otherwise if there
is no proper material directly available the demands might be higher.
Is this just an academic thought or can anybody hint me on sources to
answer this question.
Matthijs van Nie
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