Natural stone hone identification - Help

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I picked this up for $18 at an antique store yesterday. I knew it was a natural, very smooth stone of some sort, but it was covered under a lot of muck. I have been unable to determine what type of stone it is, but my initial thoughts (after much research) are Arkansas novaculite or Indiana Hindustan. There is an outside chance it's a coticule. Regardless, I think it was a good acquisition for the price. Just wonder where it might fit in my hone rotation. :confused:

To help in identification: I am located in Southern MD. The stone produces a nice, thick yellow slurry. The pictures posted are how it looks after 30 minutes of sanding on 400 grit W/D sandpaper and allowed to dry for 12 hours. It sucks up water like a sponge. One picture is a close up of the bottom of the hone. It has a small remnant of the lable that was once attached.

Thanks in advance for the help.

Chris

It doesn't seem like novaculite. It looks like slate, but, if it's absorbs water, I'm not sure. Also, novaculite, and coticule don't absorb water easily. Not even Arkansas soft or washita.
Is something written on the back side? Was the paper burned? Or it's dirt the blackening? And, does it smell like old oil?
If you lap the side of the stone, and maybe the back side, it could help. You might want to think if it's a sandstone or something similar. They are known to absorb a lot of water.
Most of the fine natural stones don't absorb water easily.
You can also test it on a piece of steel, like a knife. If it gives a mirror like finish, it's a fine stone. If there are visible scratches, it's a fine sharpening stone. If the steel looks cloudy, it's somewhere in between.

I lapped the stone yesterday and will update pictures later. To answer your questions, Vasilis, it does not smell like oil. The dark spot on the back of the stone is IN the stone. I lapped it and most of the darkening appears to have been dirt and grit. However, it did not come off easily. What was left of the label was sacrificed, but I still have a piece that fell off. The words are unreadable. The only word I can discern is "probably".

I lapped in the following grit progression: 80, 200, 400, 600.

The slur is a tan color. It is very muddy and slippery. It dries fairly quickly and leaves behind a soft paste. It smells like mud, but it's not unpleasant.

I'm leaning toward slate or sandstone, per your thoughts. I haven't found pictures of any hone that resembles this one except some of the Japanese whetstones, which seem to resemble this stone and produce a similar slurry.

After a lot more research this week, I am 99.9% sure this hone is a reasonably high quality Hindostan whetstone from Indiana, quarried in the mid to late 19th century. So until told otherwise, I will handle it as such. From what I gather, it works well with water to draw a slurry for setting a bevel. OR – it can be used with oil for mid-range (4k grit) work. I plan to use it this weekend to see what I can get out of the ole gal. I will use with water and slurry as a bevel setter. I hate working with nasty oil stones and my current low level Norton Combo India Oil stone makes quite a mess. Easier to clean up water and slurry than oil.

If it's not cutting as a bevel setter, I'll take it up a notch to use as a mid-range stone.

I've read that a Hindostan can be anything up to a 12k. Only way to find out is to use it I suppose.

Looking at your pictures I would also say Hindostan.

Just wanted to follow up on this stone. It has been lapped and put to use. I will keep the story short, but after some experimentation on a French made wedge, it works better with oil and appears to fall between my Norton 8k and my C12k. (I realize it's difficult to compare it to a synthetic stone such as the 8k.) In my judgement, it's a nice finisher with oil.

I performed this test prior to reading posts about Hindostan finishing capabilities. What I have read since falls right in line with my own use of this underrated stone. If you're a Arkansas novaculite afficinado, this would be a great finisher to a black surgical.

I would have never thought it would be a finisher with the pics and the thirst part as my Hindostan is around 2K and not consistent enough for razors...works well on knives though.

I agree with shooter74743, from the pics and description I would expect a Hindustan but not a finisher. I've lapped 2 Hindustan finishers and they can be crazy hard. I have a midrange Hindustan that wasn't too hard to lap.