On Mon, 29 Sep 2003 13:57:31 +0100, "Seamus Mc Loughlin"
wrote:

I wanted to find out some information related to stone worktops.

Stone is categorised as igneous, sedimentary or metamorphic.

Granite is igneous, which means it formed as crystals from a molten
mass. They're impermeable, hard, and chemically resistant. Chemically
there are acid igneous rocks formed from continents and basic rocks
formed from oceans, but this makes little difference to their worktop
resistance. Expensive, especially for machining and polishing, but
they're very robust.

Sedimentary rocks (limestone, sandstone) are more likely to be found
as fireplaces than worktops. They're formed of hard grains of another
rock, glued together in a softer matrix. Sandstones are quartz grains
in a minimal (and often weak) matrix. Limestones are little solids in
a matrix of calcium carbonate. They're often permeable (thus prone to
absorbing stains), mechanically weak (prone to scratches or abrasion)
and especially for the carbonates, very susceptible to attack by
acids, including citrus fruit or vinegar. Concrete may be included
with these sedimentaries.

Metamorphic rocks are sedimentary rocks that have been cooked by heat
and/or pressure. Slate and marble are the obvious examples. They're
usually mechanically strong (although this may be laminar, like Welsh
slate) and much less permeable. Marble begins as limestone and
metamorphosis doesn't change its underlying chemistry, so it's still
susceptible to acid attack.

I was reading "Concrete Countertops" at the weekend
http://www.amazon.co.uk/exec/obidos/ASIN/1561584843/codesmiths
Highly recommended for anyone considering a major kitchen worktop
project. Concrete is an interesting option and some of the techniques
apply equally to any extra-heavy worktop material.

--
Smert' spamionam