That's not slate, its BBW. I can clearly see its garnets! It's a combo end of. Slate/Schist does not have garnets.

It's not always so easy to tell though. The other day one of my friends who knows nothing about razors saw one of my combos and could not believe it occurred naturally like that, especially when he saw my Naniwa combo. He just assumed it was the same kind of thing. Even when I pointed out more closely the irregularities in the split showing him it was natural he had a hard time accepting it.