Hi Peter,

I've said it before, but a black and white approach to thinking will not
work.  There is nearly always a range of reasons for something happening,
not the single factor you seem to be clutching for.

> We should look at innovations in ore processing (preparation and smelting)
in terms of resource depletion. Development of roller crushing mills, ore
hearth smelting, the flotation process; they can all be explained as moves
to make more of the available resources.

Perhaps, but we might understand it better if we consider such other factors
as, for example, gaining better control of the processes, better management
of resources, cutting labour and other costs.  The introduction of roller
crushers to replace hand wielded sledge/cobbing hammers was a very
significant saving in the costs of employing adult males.  True, more labour
was then needed to deal with the resulting fines, but this could be done by
boys and women - and was being mechanised by the 1820s.  You mention Bucking
hammers - these were only used for breaking lumps of ore with bits of gangue
attached - not for breaking up large quantities of vein stuff.

It really is important to build a theoretical model, including all
'reliable' data, and then test and, if necessary, change it.

> certainly there is no documentary evidence and, as no archaeological
investigations have yet been carried out, there is no field evidence. What
archaeological evidence we do have is for Lyonaise mines in the mid 15th
century.

We await the archaeological work with interest, but that a mine near Lyon
used crazing mills is likely to be irrelevant.

> the ore hearth appears to have been born of resource depletion in the
English non-argentiferous sector on Mendip and quickly spread to other
mining fields in the late 16th century.

Very probably it was, but few of the other areas were having such a crisis.
My comment on gaining better control of the processes etc apply.

> the presence of 'lead ore sand', i.e. crushed galena, amongst the assets
listed in some early 16th century Swaledale (Yorkshire) wills

Who said it resulted from crushing.  Waste workers (cavers etc) would
recover discarded fine material from dumps.  It is only a small proportion
of the ore referred to.  David Kiernan talked of a smiddum revolution in
Derbyshire as the result of sieves and ore-hearths being introduced, but my
work has produced little evidence for a similar bonanza in the Yorkshire
lead fields and I am not aware of claims for one elsewhere.

Regards,

Mike