Savannah Gray Brick is awesome stuff. In "brick and a half" size, it is unparalleled in beauty. It's virtually impossible to find now, as it hasn't been made in decades, if not a century, and the process is lost. You need to find an old building to knock down to harvest them, and let the Savannah Hysterical Society catch you doing that.
Here is a good description of the Brick, and a nice picture of its attributes. My house growing up was Gray Brick, but it had been whitewashed. Still is. What a shame. Someone should sandblast that house.
I have a friend who, as a tugboat captain, found a cache, a treasure trove, of Savannah Gray Brick at the bottom of the Savannah River. It had been ballast on a vessel that sank, and he'd picked up the anomalies on his depth finder. He dove the site, saw what it was, and staked his claim. This was in 1983. There it sits, to this day. His, legally, but there is no way in hell he will ever be allowed to close the shipping channel to salvage it. The Bricks were going for about $10 to $20 apiece, I think, back then. I'm sure there are people with more money than sense who would pay upwards of $100 a brick now. He estimated there were twenty to thirty thousand of them at the bottom of the river.
Nowadays the only real use for Gray Brick is as an expensive paperweight for a Christmas present, unless you can happen upon an old house outside of the Historical District, and you don't mind rendering it into a vacant lot to collect the bricks.
Rob or Catfish may know some source, and correct me here, but I haven't seen it on the open market in sufficient quantities to build more than a fireplace in years. Course, I haint lived there in 11 years.
My favorite example of the brick? Oakleigh, on Wilmington Island. That is a Gray Brick house.
And my inadvertent use of haint for ain't reminds me to explore the use of Haint Blue paint in Savannah and South Carolina, and the voodoo culture contained therein. For another day, Intrepids.