Mystery stone... coti?

I bought this stone (in a honing paddle that looks late 19th century to me) on the Bay, assuming coti from the looks. I cleaned it up and lapped it and there were some strange things that made me doubt it's coti-ness.

First the pattern. I've never seen a pattern like that on a coti. It looks like some kind of sandstone to me.

The slurry is the bleach white I've seen on both Coticules and Novaculites, but unlike either of them (that I've experienced) when it's heavy (When I was lapping for instance) it is a BOLD gold color. It actually dyed several paper towels bright yellow on me. I also took it to the belt sander to fix some serious dishing it had, and it threw off a ton of very fine yellow powder. It seems a good bit softer than any coticule I've used before as well.

As for the edge? As good as anything I've shaved with. Right up there with Thuringians. And smooth as... something really, really smooth. I treated it like a coticule to touch up a razor finished on Thuringian by using a very very wispy slurry for maybe 40 passes, then another 50 passes or so on straight water, and it certainly didn't degrade the edge. If anything it improved it.

So, any thoughts? Is this some really really old layer of coticule that's ultra-rare or some other stone? I've never heard of sandstone hones that were this fine, but maybe? I have an inkling this is maybe a Ratisbon Hone. (Hone mentioned in some century old texts that sounds by description to be a coticule, except that it is apparently from the Ratisbon region of Germany).

http://i268.photobucket.com/albums/jj29/Lithan1/a1.jpg
http://i268.photobucket.com/albums/jj29/Lithan1/a2.jpg
http://i268.photobucket.com/albums/jj29/Lithan1/a3.jpg
http://i268.photobucket.com/albums/jj29/Lithan1/a4.jpg
http://i268.photobucket.com/albums/jj29/Lithan1/a5.jpg
http://i268.photobucket.com/albums/jj29/Lithan1/a6.jpg

Interesting...I was watching that auction as well and was certain it was a coti. However, those weird swirl marks are different than any I have seen.

Regardless, sounds like a very good stone!

Yeah I didn't even consider that it wasn't a coti. Then it got here and once I had it in hand I got a little worried that it was some kind of low grit sandstone. That was a possibility right up until I was ready to shave. Then there was that "Awwww... yeah" moment when you have a razor you're not 100% on and it just whispers right through your beard leaving nothing but nothing in its wake.

SliceOfLife said:

Yeah I didn't even consider that it wasn't a coti. Then it got here and once I had it in hand I got a little worried that it was some kind of low grit sandstone. That was a possibility right up until I was ready to shave. Then there was that "Awwww... yeah" moment when you have a razor you're not 100% on and it just whispers right through your beard leaving nothing but nothing in its wake.

Click to expand...

Coti edges almost always do this to me! They don't feel sharp, but it really seems that a coti edge just seeks out hair only.

As for your stone it really doesn't look or sound like a coticule. I don't know enough about modern hones, let alone vintage hones in general to help you unfortunately.

Pretty much the one person I'd really trust to say definitively if this is possibly a coticule or not would be Bart.

He's probably the best qualified for that task, and hopefully he will give his opinion... but he's always quick to note that his experience is largely with the small number of veins that Ardennes currently is cutting away at, so I wouldn't be surprised if even he couldn't give me a definite answer on it.

Oh and the stone also has slight hints of green to it, which I've never seen on a coti. I forgot about those (very slight).

Looks like cut and polished chert, to me.

I can't be of much help, I'm afraid. It looks like a possible Coticule, but if you say that it behaves very differently... it might very well be something different.

The pattern is not not impossible though. I have seen Coticules with that kind of molten aspect. I'm attaching 2 pictures of Coticules without any doubt. Both are lapped with a very coarse lapping plate, so there are some swirl marks.

Regardless of the color of a Coticule, the slurry is always very pale, with only a slight hue of the stone color. Green is possible, as are yellow, pink and even a deep red. But the slurry is always pale.

A while ago, Cedrick Smythe and I did some critical source tracing about the "Ratisbon" hone. Ratisbon is the old name of Regensburg, Germany. It seems to all revert back to one single source, that was copied by a few later authors (exactly the same phrasing). We could not find any further traces of whetstones coming from the wide Regensburg area. Belgischer Brocken Vertrieb
Steffen J. Lindner, the owner of "Belgischer Brocken" in Germany, lives in the Regensburg area. He had been researching the science and history of Coticules since many years. I would expect him to make reference on his website to a "Ratisbon Coticule", if such a beast would really exists. Perhaps you could contact him and pop the question.

Kind regards,
Bart.

Wow Bart. Thank you. And damn those stones are stunning. Either of them for sale (especially the one on the right)?

The slurry was definitely a very deep yellow, so it's interesting that you've not found coti's able to get anything but faint colors in the slurry. The stone is very thin (like most coti's) so I'm wary of doing any more heavy lapping, but I might do a chamfer (or lap the back) or something later just so I can snap a pick of the slurry. It'll have to wait until I can do it in good light though.

I'll try and get an email out to the fellow you mention. Do you know if he speaks English? I got along acceptably well in emails with Mueller using an online German translator, but I doubt I could convey the sort of complex/technical questions and details that may arise by way of a translator.


Woodash, the only Chert pics I'm finding online are artifacts that look very porous. Do you have any pics of something along the lines of a chert hone to see what it'd look like in this state?

SliceOfLife said:

Woodash, the only Chert pics I'm finding online are artifacts that look very porous. Do you have any pics of something along the lines of a chert hone to see what it'd look like in this state?

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SOL - chert is anything but porous; it’s actually very dense and hard and very fine-grained. Think flint, for example. Flint is essentially just a dark chert. I would bet that if you chipped your hone, you would see a very nonporous rock with the kind of concoidal (or 'breakage') fracture that you associate with the edge of arrowheads, etc.

Chert is basically a microcrystalline or cryptocrystalline variety of quartz that typically forms as white or light gray nodules or concretions. It commonly has these characteristic concentric growth bands that I see in your stone. They are sometimes interspersed with zones of different color (yellows, reds, etc) resulting from incorporation of Fe-oxides, organics, etc. Flint, jasper, chalcedony, agate, etc. are all more or less the same stuff with different color zonation resulting from different impurities/inclusions. Novaculite/Arkansas stone is also a chert with little to no impurities and some noncrystalline (opaline) silica.

There are plenty of pics of chert out there, but not too many of polished sections. Here’s a generic banded chert that was later made into an arrowhead:

The following thread posted to SRP a while back also shows a hone that I also believe is banded chert:
http://www.straightrazorplace.com/forums/hones/55342-lucky-stone.html

In any event, personally, my guess is that you’ve got a nice piece of chert there that would probably make a good hone. But aside from all these pictures and my little essay here, I base my opinion mostly on having seen a ton of chert in many places over the years. I could well be wrong, but from what I can see in a few pics, it sure looks like chert to me.

Good luck with it, whatever it is.

When I read gold slurry, dense and smooth stone, and saw the photos it made me immediately think of these:





These stones weren't orange all the way through, but I have other rocks that are a creamy orange top to bottom. These stones produced a golden yellow slurry when l lapped them on the orange side. The photos show them dry, and when I wasn't done with them. The pattern on the face is different layers showing up. If you lap the side of your stone and see multiple layers, I would say that your stone might be a Hindostan whetstone.