Does anyone know of any natural hone that produces a red-ish/brown slurry? I ask because I have a natural stone that's doing the job of honing very well, but the slurry colour is redish brown, due to high iron oxide levels in the stone... (iron oxide being used as an abrasive compound I feel this all makes sense, but just wanted to know if any other natural stone produces red/brown slurry..)

Thanks for any replies.
- Mike