Marble resistance to Weather

[Don Dougan <dondougan@zzzzzzzz>]

Bill;

For what it is worth here in the States, the best weathering marble is
 from the Georgia Marble Company.  You can see some samples of marble
color/structure online at their website.

Georgia marble (quarried from Tate) has a very large crystalline
structure and very low porosity which combined means the surface is more
resitant to the effects of water.  Obviously, acid rain will still attack
the calcium carbonate.

Looking at old gravestones here in Georgia climate, the local marble is
much better at retaining surface detail than the 'finer' Italian marble
which was favored for figurative monuments a hundred years ago.

As far as carving:
Depending on the type of work you do, Georgia marble may be too coarse
for fine detail - compared to Carrara white, carving Georgia white is
like the difference between rock salt (Georgia) and  confectioner's sugar
(Carrara).  Lifesize figures can be worked welll in Georgia marble, but
the large proportional size of the crystals in working smaller than
half-life size is an issue when trying to achieve a high degree of
detail.
Personally, I prefer to work in finer-grained stones - but most of my
work is not intended for outdoor placement.  When I do get the odd
commission for an outdoor piece I use Georgia marble for it's weathering
qualities, and I use textured or honed surfaces (not polished) .

Good Carving to You,
Don
http://www.dondougan.com