David Weaver
This stone appears to be an extra fine india or something of the type, but it's flat and near perfectly covered on all sides and edges with a layer of grease or something to shut down its cutting ability.

I've seen washitas maintained like this to sharpen razors, but this stone is from japan. These stones without being coated like this will cut evenly, relatively fast and leave a pretty strong wire edge.

tried with water

Tried with a dot of mineral oil (didn't try first as I was afraid it may remove the coating).

Interesting result -very slow, but look at the edge where finger pressure is concentrated.