Ok, even though I asked about readily commercially available stones, the information I got back from Alex at thejapanblade.com was unbelievably detailed. I was getting little information about other stones from retailers. I understand that natural stones are always a risk, but for the price the stone is worth the risk. If anyone is looking for a Japanese natural hone, Alex is your guy. When I get the stone I'll post a review. Thanks to everyone for the advice.