availability of stone

[Norman Watts <Norman_Watts@zzzzzzz>]

I spent about three hours yesterday with the manager, a geological
engineer, in a Virginia granite quarry. I learned all kinds of
interesting things about the operation and quarries in general.
Probably the most striking thing he told me is that on average the
quarries in the world recover only about 10% of the stone, the rest
of it goes to trash. Either the stone is damaged (say in blasting) or
not of the regular dimension required for sale. The rest goes to
tailings. In their case it wasn't even cost effective to run their
waste across the road to another bunch who crush stone. Amazing. On
the one hand you'd think that the world is made of stone and you'd
never run out of it, but on the other its clear that good quality
stone must be limited, particularly stone that is not covered with
development or in areas where people will resist a quarry. As I was
driving home through the lovely Virginia countryside I heard another
remarkable statistic on the radio. It was recently estimated that in
the US, one third of the available copper is in the ground, one third
is in use, and one third is in the trash somewhere. One quarter of
the earths accessible copper is already in use.

n