We are grateful to the National Trust for allowing us to place this cache.
Parking is available at the coordinates given below, which are for the verge opposite the pub.
There are open, unfenced mine shafts and cliffs in the area of GZ, so please keep dogs on the lead and children under close control
Overview of the dressing floors at Porthmeor.
Dressing floors are the area on the surface, where ore was concentrated.
The first stage in processing the ore was breaking it into small pieces using stamps.
There is no sign now of the stamps that would have been in use on these dressing floors, but here is a restored example at Geevor.
Restored stamps at Geevor.
Mechanically, stamps were very simple. The water wheel turned a central cam with blocks on it. These blocks engaged with corresponding blocks on the vertical part of the stamps (the stem). This lifts the stem with it's attached heavy head, then allowing it to fall on the ore below.
The wheel pit, pictured here, would have house a water wheel which would have powered the stamps.
Wheel pit at Porthmeor.
After being crushed into fine enough pieces, the ore would have been washed into the buddles.
Buddles had a raised centre onto which the ore was washed. The heavier tin ore fell to the bottom of the buddle, while the lighter rock was washed into the water channel which is visible behind the buddle in the photograph. Rotating brushes were used to keep the surface of the ore level. After a few hours, the water flow was stopped and the concentrated ore dug out.
The final stage of processing at Porthmeor would have been the reverberatory calciner, where the ore was heated to drive off impurities such as arsenic. The reverberatory calciner was an improvement on the original design where ore was mixed with the fuel, in the reverberatory calciner they were separated, thus reducing contamination of the ore.
This photograph shows the remains of the flue which connected the calciner to the stack which provided the draw.
Calciner and flue at Porthmeor.
Anyway, none of this helps you with finding the cache, which is at:
N re-mail-ck systat emfis-cntl W rje 36 sfs-smp-net
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