Dear Peter,
These are unlikely to have anything to do with ancient metal working.
The chemistry does not make any sense.
Are you sure that they these are not part of the local geology -
zeolites are known authigenic minerals in sandstones and other
sedimentary rock. Some partially mineralized sandstones and some
weathered sandstones can be very blocky and look like abraded building
materials. Is there any evidence of working - Chisel marks, old
unabraded fractures?
The best thing to do is to talk to a local geologist.
--
Chris Salter,
Oxford Materials Characterisation Service,
&
Electron Microscopy Research Support Group,
&
Material Science-based Archaeology Group,
Oxford University Begbroke Science Park,
Sandy Lane, Yarnton, Oxford, OX5 1PF
Tel 01865 283722, EPMA 283741, Mobile 07776031608
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