Carrara marble

I will be interested in the responses to Andrew Thorn's query about
the composition of Carrara marble.

Two years ago we drove around the Carrara quarries (a fascinating
experience with the world's steepest roads with huge trucks
ascending 6,000 mountains which are being dismantled). We brought
home some pieces of grey waste rock lying by the road and I have
noticed it has become progressively paler and now has a very white
crust. This could be due to the superior climate in England to Italy
but more likely the rock is reacting with the air and changing
chemically since it was first exposed. This is the opposite of what
happens to most materials, which darken. No doubt this sun/air
bleaching effect is part of the reasons for the popularity of the
quarries. Most archaic marble looks pretty white although it can
appear yellow or streaked.

Simon Green

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                  Conservation DistList Instance 12:90
                   Distributed: Tuesday, May 25, 1999
                       Message Id: cdl-12-90-007
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