On Wed, 02 Sep 2009 16:39:06 -0400, Jim Elbrecht
wrote:

-snip-
I've seen split granite pavers & slabs at some hardscaping place or
other.
-snip-

This isn't the place I saw them, but it is pretty close to what I
remember seeing-
http://www.newenglandnativestone.com/prodpages/gr1.html

They should work nicely for what you want-- and they shouldn't be
slippery when wet.

No big box and few lumber yards are going to know this stuff is even
out there. Start at a local quarry and work down tot he retailer.

Jim