Stone identification process?

[Naftoor]

As I’m going through threads trying to identify one of my own rocks, I’m realizing similar questions seem to be asked every few months. At the same time this place seems to be one of the greatest concentrations of rock hounds, polishing masochists and sharpening stone historians on the English speaking internet.

What’s the general process for identifying strata for a stone, assuming you either know nothing or don’t have reliable information on the rock before it comes into your possession?

I know SG is pretty standard, but I imagine there can be quite a bit of density overlap between various rock types?

Similarly scratch tests don’t seem to be super beneficial since all it does is give you a general hardness range. I know the advanced advice is to find a rock hound club or go to a geology department at a nearby university, but I imagine there’s some interim steps that can be taken between weighing a rock and taking it to an expert no?

 

[ptolemy]

Best advice I could give is to post detailed pictures here and let the community help you. Also, keep in mind that unless the pattern is fairly rare or unique to few mines, there could be 5 educated guesses, but also they might be 100% wrong. I seen so many stones that may look like a $1500 one that end up being a $50 ones.

In the end, the only thing that's important (unless you can prove beyond any doubts) is the stones actual performance.

 

[Naftoor]

Fair enough, I’ll drop what I know. Not a fancy Jnat, but I’d love to find out the rock type so I can source additional ones in the future since the original source is dried up.

These guys were once sold by cris from scorpion forge. From what I found from him on the forums he originally advertised them on, he mentioned he sourced them from a fellow in Russia who had them in a rather limited supply.

Characteristics:

Very hard, they’re as flat as when I received them with no signs of dishing that I’ve noticed.

Grit seems to be somewhere in the 1-3k range. With heavy pressure I’d put it as being fairly similar in burr raising speed to the kuromaku 1000, with lighter pressure it’s speeds are similar to the spyderco extra fine bench stones.

Fed it spyderco S30V, CTS-XHP, Nguyen 52100, markin UX-15, Enzo VG10, herder buckels mystery stainless and takamura chromax amongst a few others. It’s never struggled with any of them. At most I do light microchip removal but in general most of my sharpening is just refreshing the edge. Generally only 5-10 strokes to raise a burr.

Does not absorb water, basically at all. 95% of it just beads up and runs off while sharpening so I’ve taken to using dish soap for the surfactants to make the water cling to the surface better. Swarf is minimal, only noticeable on longer sharpening sessions, most tends to adhere to the stone and needs scrubbing with a non-abrasive sponge to remove it.

Feels nice to sharpen on. I’d describe it feeling like glass covered with a microfiber cloth. Still very hard, but not as unpleasant as the spyderco ceramic stones.

Lovely greenish grey color.

Specific gravity puts it at 2.73

Originally with google-fu I thought it might be songhua/sungari, a natural stone out of china. Apparently the mines been closed for awhile and they were well liked in russia where some slabs could still be found in warehouses. The location made sense, in addition the last image in the article matches fairly well with the rock. Now I’m not sure though, I’ve got hunks of nephrite and they are frankly awful sharpening stones. No grit, really just a hone which doesn’t line up with how these stones perform at all.

 

[stringer]

It looks like a lot of the Chinese stones. Either a songhua or a Guangxi. They are usually described as very fine, hard, and slow. But there is a ton of variability. Maybe you got a fast one. Or maybe it's something else entirely.

I don't have much of an identification process, despite the fact that I've pretty much exclusively purchased unlabeled natural stones of indeterminate origin for the past several years. I will look on eBay and the Internet for similar images. But mostly I just ask here and on Badger and Blade if I can't figure it out. And most of the B and B stonehounds are here too nowadays. But for a lot of stuff there just isn't going to be a simple answer.

Good luck!

 

[Naftoor]

Thanks @stringer ! I figured it wouldn’t be as easy as I hoped. Looks like my best bet is to keep buying them every chance I can when they appear so I can inconvenience my descendants with a large amount of unlabeled, non-descript rocks located in a safe under my bed for reasons they’ll debate long after I’m gone

 

[stringer]

Thanks @stringer ! I figured it wouldn’t be as easy as I hoped. Looks like my best bet is to keep buying them every chance I can when they appear so I can inconvenience my descendants with a large amount of unlabeled, non-descript rocks located in a safe under my bed for reasons they’ll debate long after I’m gone

 

[cotedupy]

As I’m going through threads trying to identify one of my own rocks, I’m realizing similar questions seem to be asked every few months. At the same time this place seems to be one of the greatest concentrations of rock hounds, polishing masochists and sharpening stone historians on the English speaking internet.

What’s the general process for identifying strata for a stone, assuming you either know nothing or don’t have reliable information on the rock before it comes into your possession?

I know SG is pretty standard, but I imagine there can be quite a bit of density overlap between various rock types?

Similarly scratch tests don’t seem to be super beneficial since all it does is give you a general hardness range. I know the advanced advice is to find a rock hound club or go to a geology department at a nearby university, but I imagine there’s some interim steps that can be taken between weighing a rock and taking it to an expert no?

Fair enough, I’ll drop what I know. Not a fancy Jnat, but I’d love to find out the rock type so I can source additional ones in the future since the original source is dried up.

These guys were once sold by cris from scorpion forge. From what I found from him on the forums he originally advertised them on, he mentioned he sourced them from a fellow in Russia who had them in a rather limited supply.

Characteristics:

Very hard, they’re as flat as when I received them with no signs of dishing that I’ve noticed.

Grit seems to be somewhere in the 1-3k range. With heavy pressure I’d put it as being fairly similar in burr raising speed to the kuromaku 1000, with lighter pressure it’s speeds are similar to the spyderco extra fine bench stones.

Fed it spyderco S30V, CTS-XHP, Nguyen 52100, markin UX-15, Enzo VG10, herder buckels mystery stainless and takamura chromax amongst a few others. It’s never struggled with any of them. At most I do light microchip removal but in general most of my sharpening is just refreshing the edge. Generally only 5-10 strokes to raise a burr.

Does not absorb water, basically at all. 95% of it just beads up and runs off while sharpening so I’ve taken to using dish soap for the surfactants to make the water cling to the surface better. Swarf is minimal, only noticeable on longer sharpening sessions, most tends to adhere to the stone and needs scrubbing with a non-abrasive sponge to remove it.

Feels nice to sharpen on. I’d describe it feeling like glass covered with a microfiber cloth. Still very hard, but not as unpleasant as the spyderco ceramic stones.

Lovely greenish grey color.

Specific gravity puts it at 2.73

Originally with google-fu I thought it might be songhua/sungari, a natural stone out of china. Apparently the mines been closed for awhile and they were well liked in russia where some slabs could still be found in warehouses. The location made sense, in addition the last image in the article matches fairly well with the rock. Now I’m not sure though, I’ve got hunks of nephrite and they are frankly awful sharpening stones. No grit, really just a hone which doesn’t line up with how these stones perform at all.

Good q.

The answer is basically (as you’ve kind of guessed) that, short of having access to expensive scientific equipment to test something against a known example - there isn’t really a set and definitive method for this kind of thing. It relies on a number of factors to do with experience, knowledge, and research coming together. And pretty much all of the assumptions you’ve made about important things to consider are correct.

SG is useful because it’s something you can measure easily and objectively at home. But as you say, there can be overlap. It becomes less useful when trying to exactly identify grey slates and schists without any defining visual markings. All it will do is tell you that it’s a grey slate or schist (your stone looks and sounds to me like the latter).

Scratch tests aren’t particularly helpful because they’re used to identify the Mohs hardness of individual minerals, whereas almost all sharping stones are composites of different minerals in a matrix. Steel can scratch the surface of a whetstone without scratching the abrasive Silica or Alox within it.

Considering where you got the stone is very useful. If you bought it at a rural boot sale in the middle of America it’s unlikely to be an Asian stone (unless perhaps there was a large Chinese expat population). If you got it from a Russian ebay seller it may well be.

There are various other factors, and in essence you want to try to identify aspects that are unusual, to narrow the field and rule things out. And to that end your stone does have one particular thing that stands out to me: its size. Traditional western natural stones were very rarely cut more than 2” wide. I can’t tell for certain from the pics, but if your stone is more than 2” wide and 8” long, as it appears to be, that would certainly support your theory that it might be Chinese.

There are a couple of other things that might too: Schists were rarely used as benchstones in the West, it’s far more common to find them as scythestones. There are some French examples, but usually for this kind of coarser whetstone it would be more common in Europe and the US to use sandstone. And yours isn’t a sandstone because of the SG, so again that might support the idea that it’s Asian. It’s almost certainly not Japanese, so China might well be a good bet.

I’m usually wary of making niche suggestions to stone ID questions. But in this instance - you could well be correct, especially if the assumption I made about the size is correct.

 

[cotedupy]

The location made sense

What did you mean by this btw?

 

[Naftoor]

What did you mean by this btw?

So the guy who originally cut them bought them in pretty massive slabs, from a Russian supplier. He used to cut something like 8-14 of these stones from per slab. I sourced a few larger stones that are inbound, which are 8”x3”x2”. Most of my current samples of it are more like 8”x2.25”x1.75”.

No idea how many slabs he did but it sounds like (from the forums he sold them on) he did at least 4-5 of them before the supply dried up. The article I linked made it sound like a non-insignificant amount of the remaining sungari stock ended up in warehouses, and were particularly loved in Russia so it made sense that maybe a few hunks of the stuff ended up in a Russian suppliers hands. I’m not sure I fully trust the article however, because again they talk about sungari being a type of nephrite. I have some nice nephrite samples sold as whetstones (unfortunately yes, THOSE ones that get talked about on badger n blade) back from when I was only slightly dumber about sharpening stones then I am now. That stuff essentially doesn't cut steel. It’ll do an amazing job on its first knife after the surface is refreshed and cut steel like a file, and from the second knife onwards basically becomes a burnishing rod. Maybe useful for razors, with which I have no experience, utterly worthless for knives which this stuff is definitely not

 

[Naftoor]

So I asked cris directly, he said his supplier never told him anything beyond the stones are from a mine in china. Doesn’t really narrow things down much unfortunately given the size of the country, the language barrier to learning about the various mines and the way Chinese stones never seemed to rise to the same reverence as jnats/Western European stones/american stones so not as much information seems to be available. May try bringing one of them to a universities geology department to see if they can tell me anything, but otherwise I’ll just be glad I found them

 

[cotedupy]

So the guy who originally cut them bought them in pretty massive slabs, from a Russian supplier. He used to cut something like 8-14 of these stones from per slab. I sourced a few larger stones that are inbound, which are 8”x3”x2”. Most of my current samples of it are more like 8”x2.25”x1.75”.

No idea how many slabs he did but it sounds like (from the forums he sold them on) he did at least 4-5 of them before the supply dried up. The article I linked made it sound like a non-insignificant amount of the remaining sungari stock ended up in warehouses, and were particularly loved in Russia so it made sense that maybe a few hunks of the stuff ended up in a Russian suppliers hands. I’m not sure I fully trust the article however, because again they talk about sungari being a type of nephrite. I have some nice nephrite samples sold as whetstones (unfortunately yes, THOSE ones that get talked about on badger n blade) back from when I was only slightly dumber about sharpening stones then I am now. That stuff essentially doesn't cut steel. It’ll do an amazing job on its first knife after the surface is refreshed and cut steel like a file, and from the second knife onwards basically becomes a burnishing rod. Maybe useful for razors, with which I have no experience, utterly worthless for knives which this stuff is definitely not

Ah gotcha! Sorry - I slightly misread your original q. / didn’t read your 2nd post closely enough, and so answered in a more general way. (Hopefully somebody might find it useful though!).

But yeah - there’s no way you’ll be able to tell exactly where in China it’s from. Unless you happened across something near-identical in a quarry and then ran some quite elaborate tests on the pair of them.

In terms of stone type though: I’d pretty much guarantee you it’s not nephrite. I think it’s a schist, or very coarse slate, or something halfway between the two.

 

[Naftoor]

Makes sense, thank you Oli!

 

[Desert Rat]

I think there are a few stones mined in Russia and probably more in the Eastern Europe.

https://jnats.eu/en/product/technin...Hrd_Zzd-WX7fPtnlfVeaEFgXUKwVIA-PdCo12b6RXoyoP

 

[Desert Rat]

Here is a link that has some information on a few of the Russian hones as well as some others.
Need to translate.

http://zatochiklinok.ru/1-2/naturalnye-abrazivy

 

[Naftoor]

Oh those were fascinating reads. The technical jaspers described seem to be pretty close. Ultra hard, cuts most steels without many issues, decently quick for how fine it, very homogenous visually, grayish green, and that would align with the original source of the slabs being a Russian supplier. Got a picture of a broken edge on one of them, which to my eye looks similar to what I’ve seen on leftover hunks of granite countertop. Google says granite fractures conchoidally, which the article also points at. Think I’ll try it with some mineral oil to see how it behaves.

The guanxi stones also seemed to have some visual similarities, but they describe them as being 10k+ stones which doesn’t align with anything I’ve experienced

The many images of them whittling hairs reminds me that as always, I am not limited by my stones, but by my crippling inability to sharpen properly,

Also, downside, googling anything related to “sharpening technical jasper” gives you all of those ancient ocean jasper videos which is definitely not what I want, thanks google. This must be what it’s like to share a name with someone who’s infamous.

 

[Naftoor]

Deleted due to odd double post

 

[stringer]

I don't think it's technical jasper. Your stone is made up of little bits. The Jasper I have had is smooth like glass with no visible bits. Much more like translucent Arks and quartz. And definitely in what I would consider the 10000+ grit range. Extremely slow and fine.

 

[Naftoor]

So this image is what I found curious, the images look to my eye to be very finely grained, homogenous, grey green which looks very similar to these ones. I agree that most of the jasper sharpening stones I’ve run into look more like polished gemstones, again that ancient ocean or Apache. They had a link to some old Russian forums with a discussion on it, (https://forum.guns.ru/forummessage/224/1199536-4.html). It amazes me everyone is worried about ChatGPT taking everyone’s job when google translate 20 years in service still can’t translate anything past a few words into legible english. I’m wondering if there’s a few stones confused as one another. The photos they share range from that one I posted below which is fine grained and homogenous, to speckled stones that look like traditional jasper. I’m suspecting there’s some mixed identities because they report wildly different results as well, but I’m also guessing google translate is wrecking a lot of the information as well.

The search continues I guess

Edit: More reading on that Russian language thread and I’m thinking maybe it’s not this stuff. A few of them talk about how it struggled with X or Y steel, past just polishing the edge up. I watched this stone eat vg10 for breakfast. I need to break out the kuromaku 1000 to refresh my memory but it had to be at least that speed when thinning. A couple of strokes of heavy pressure which I don’t tend to use and the water just turned to swarf

 

[Naftoor]

Likely of interest to no one, but I was bored and decided to pull out the half forgotten 250x pocket microscope I originally got for looking at bevels and immediately decided was too much effort for sharpening.

Took some shots in groups of 3 of the mystery stone, a washita I picked up from oli years ago, a translucent ark pocket stone, kuromaku 1k, and that hunk of nephrite. I apologize in advance for the post notification spam but I have no idea how to cleanly separate them into individual stones otherwise.

 

[Naftoor]

Mystery stone, 250x

 

[Naftoor]

Washita, 250x

 

[Naftoor]

Translucent ark, 250x

 

[Naftoor]

Kuromaku 1000, 250x. Dark speckles in first image in particular are swarf remains

 

[Naftoor]

Wyoming nephrite, 250x

 

[dabes]

going off the photo of the dented one, could be a 2k guangxi it has a similar surface finish w/ diagonal lines too

https://www.ebay.com/itm/3226174103...25F6KN&hash=item4b1d7f0315:g:k6cAAOSwyWZZUWkp