Black Arkansas Definition
If you were interested on how their black stacks up
"The Black Arkansas is the finest stone that we manufacture. It can be finer than the Translucent Arkansas and True Hard Arkansas stones. It has a very smooth and glassy feel to the stone. It will help you to achieve a razor sharp edge. As you have found that there are companies out there that are marketing the Black Arkansas stone that are not genuine Novaculite stone products and they do not perform the same as our Black Arkansas (novaculite stones) do. They tend to be a softer material and do not produce the same time of finished edge."
Again Kim's words from Dan's whetstone company.