It's not a natural stone. The grit is around 8k, as best I've been able to tell. It's certainly not 12k, and if it was, no strop dressing would be needed.
It's recommended to keep the hone away from heat sources (like a radiator), as the heat will cause the binding agents in the stone to break down, which makes the hone even more fragile and prone to breakage than it already is.
The Rolls razor instructions say the stone should be used dry. Myself and many others have noticed that smearing the hone with petroleum jelly, letting it sit for a few hours, and then wiping it off, seems to rejuvenate the hone, and gives a much better edge to the blades, and when combined with a pasted strop, allows the Rolls blade to be brought to a shave ready state with no need for equipment beyond the Rolls's own sharpening system.