Stone ID assistance

Just picked this up from a bin in which my father had several Arkansas stones (mostly smaller stones and sharpening kits). I'm visiting family and don't have time for proper research, but interested if anyone might recognize the stone or the stencil type labeling. It is about 6" x 2 " x 3/4", has inclusions and saw marks. Looks to have some sparkle in the sun and feels fairly fine to the touch.

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Does it slurry easily, if so what color?

With family a day, will follow up this evening w more info

Was able to sneak away for a few minutes to take pics, could this be a synthetic Stone? Not much of s muddy smell, and very green fine slurry after some hard rubbing.
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Now that’s weird. The only stone I have that makes a slurry like that is a light green slate, but it is soft and slurries easily. Slurry is dark pea green. It is a nice finisher, similar to a Thüringen. It is stamped on the side Seneca Stone.

The chips on the edge will be hard to lap out. The chips look flaky like a hard novaculite, but a black ark will slurry white, and is hard to slurry.

I thought the “C12 15” might indicate Chinese Guangix stone, they were originally marketed as 12k’s and called C12k’s, but were also marketed as 12-15k, though they are not. They also slurry white.

It may be there is something on your stone, oil or old slurry a good soaking in Simple Green or Awesome and scrubbing with a scotch brite may clean it up. It may take a week or so to clean up. I have soaked hard stones for months to remove oil.

What does the bottom side look like, lapping that side may be easier?

Thanks for adding more thoughts on this stone. It smells of oil, but not thick at all. Both sides are pictured above, there are some differences noticeable in the inclusions, but the light ridges look very similar, but hard to feel. There are some sparkles that show up in sunlight, could this be something from the UK? My dad had probably had it for many years. I'll put a razor on it after I get home on Thursday.

Few pics this morning, I do have a Llyn Idwal, and this stone doesn't seem to chip in the same flakey way.
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Back home and getting to work on this hone. Set out to get the thing flat beginning with least aggressive methods; here is how that is going to far:

Started with 400 w/d sandpaper on a little glass table. The stone happily ate up the paper, so I picked up some 220 and 180 and still didn't get much progress
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I did use a little cell phone magnifying thing to capture a few pics of the higher spots that took a bit of a shine:

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Did more reading here on lapping hard stones, and figured I would use the belt sander w a new 80 grit belt. First I worked on the back side to ensure I don't ruin anything, that was alright so did about maybe 20 minutes total time on the better side of the stone. The stone got pretty warm, and I still didn't feel like I was making solid progress, so I ended up scrubbing this thing on the back porch concrete. Worked up a good sweat doing this for about 30-40 minutes.

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Taking a break and tending to other responsibilities for awhile today, but at least now I can see that I'm making progress, the center of the stone seems to be higher - hoping I can finish up later today.

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I still have no idea what this is, although I'm leaning towards some type of Novaculite.

Will the inclusions be detrimental to honing?

if i were to find that in a store i would assume that it's man-made, mostly because of the bubbles and just the overall look.

The super green slurry is very cool. Cant help ya in what it is, but a nice find if nothing else. My understanding is the holes could be an issue. If the blade edge goes across and hits the other side of the hole you can imagine some damage to the edge.

Here is the rest of the lapping story. While tired and still making a mess on the back porch, I thought, "well, I might as well try the 400 diamond plate and see what happens." I had previously discounted this idea, because i didn't want to unnecessarily wear it out on this hard stone. But I was ready to make some different muscles sore, so I went to work. It was amazing, dark green slurry poured off of that thing and I was done in maybe 15 minutes and able to progress on to finer sand paper.

I took a carbon steel razor that already had an edge that I liked, and gave it 20 laps at a time until the new scratch patter had replaced the previous polish (around 150 total light pressure laps maybe). It's appearance was somewhat harsh but consistent, maybe visually comparable to a 4k-5k pattern. I was skeptical that it was fine enough for a shave. After untreated linen and leather, I was getting very good HHT results. The next morning's shave was 8 out of 10 keen and about 4-10 comfortable; overall not very pleasant, but in the name of science I completed my normal routine without swapping to a different razor.

Overall impression is that this is just an odd stone. I believe to be a natural stone (do any old synthetics show cutting wheels marks on every side?). I will probably give it a go as a pre-finisher, but that isn't really a process I would normally use. In any case, I acquired it from my dad who thinks he might have gotten it from his father, so it will certainly remain a very important part of my humble collection.

-Mickey