Marble resistance to Weather

["Simon Brown" <moonsong@zzzzzzzzzzzzzzz>]

Bill,

There was a brief but interesting discussion on the hardness of marble a
while ago: http://home.clara.net/pst/list00/msg00892.html

The resistance to acid rain depends on the percentage of Calcium Carbonate
in the stone. You can carry out a simple test by putting a few drops of
dilute acid on the stone- if it fizzes, CaCo3 is present and the stone is
liable to be affected by acidic rainwater.

Marble used outdoors is traditionally left at a honed finish because a
polished surface is soon removed by the sun and rainwater. There is a
descriptive article here: http://pubs.usgs.gov/gip/acidrain/5.html

An indirect source of acid can be sulphate-rich bands of limestone in a
building. The acid is dissolved by rainwater and washes over other stones
prone to attack:
http://www.doc.mmu.ac.uk/aric/eae/Acid_Rain/Older/Buildings.html

Simon