Thread: carborundum?

Just trying to figure out if this is a carborundum. I bought it thinking those layers meant it was a real stone, but it sure is soft and easy to lap...not that I'm done. Slurry seems to be pretty much black, definitely no purple hue. Under 30x I see some red, but I don't think it's the garnets people are talking about with thuringian. Then again, what do I know? Any input? Maybe slate? Sure seems heavy for a man made stone.