Help with an antique shop find

[Rivers310]

Hi there, I recently purchased this at an antiques shop. It was labeled “barbers hone”. Dirt cheap, I couldn’t walk away. Lapped the bottom side and finished it on 2k. The wear on the face was evenly worn. Looks more blue with the camera/ greenish blue in daylight. I’m comparing this to one of my best finish stones, which is a hard la dressante. Fast on slurry, slow to finish. This stone is moderate on slurry and slow on water. I finish till my blade starts sticking. Leaves a really sharp blade but not as smooth as the coticule. I’ve also noticed that some razors are hit or miss. Which means I need more practice on this. Any idea what this might be? And also, I like the smooth shaves coticules leave, would using honing oil tame that edge or just make it sharper?

Forgot to mention some other comparisons, it’s harder than coticule. Reminds me more of my charnley forest.

[outback]

Only thing I can say...looks like a type of slate.

[Rivers310]

Can’t figure it out, the way the slurry looks. I can get slurry on the charnley but I’m sure that’s from the slurry stone. feels like a really hard slate. After working with it for a few days I thought I would’ve figured it out. I’ve had a few hard Arkansas and charnley forest I’ve passed along. Not too familiar novaculite other than the two mentioned above. Next to the coticule and charnley

[outback]

Put a razor to it, see what its capabilities are.

Made a couple slate hones, myself. They will bring an edge to around 8k. then take it to a pasted strop. It shaves pretty good.!