Strata Bambata

Tomae Awasedo.jpg

Jnats – The Strata Bambata 

So, what’s in a name?

When anyone looking to purchase a Jnat, or Tennen Toishi, from any source, the first thing they see is the title or name of the stone in the page listing. Monikers such as Nakayama Asagi, Sobudani Karasu or Ohira Suita abound.

These names, and many others, follow a convention of sorts, but that styling isn’t always consistent from seller to seller.  

So – When we read ‘Nakayama Asagi’ – we have the name of the mine first ‘Nakayama’ and the ‘color’ of the stone second, ‘Asagi’ means the stone can be green or blue/grey/green or even have a mix of yellow in it.

When we read Shobudani Karasu’, we are missing the ‘color’ – but we have the pattern known as ‘Karasu’ listed. Technically, in a non-existent perfect world, this would be called a ‘Shobudani Asagi (or whatever color) Karasu. The listing of ‘Mine’ ‘Color’ ‘Pattern’ is a typical convention, but like I mentioned, sometimes things aren’t always done ‘perfectly’.

Then, sometimes, we see the name of the ‘Layer’ listed in the name. ‘Nakayama Asagi Tomae’ is such an example. We can also find listings titled ‘Nakayama Tomae Karasu’, where the color is missing but the pattern is listed. A comprehensive naming convention would list everything, so it might be called out as ‘Nakayama Asagi Tomae Karasu’ or Nakayama Asagi Karasu Tomae’.

While there is an accepted & correct way to handle the names, that’s not the point of this essay. The forum geeks can have that argument; quite frankly – it’s about as important as tits on a bull. 

Because we find all kinds of naming conventions, and any one seller might not even be consistent within their own listings, perfection takes a back seat to reality. The important thing is to be able to identify what the ‘parts’ of the names are. This way – no matter what order they’re in – the stone can, usually, be identified with reasonable ease. 

This essay is about the part of the stone’s name that calls out the strata, or layer, vein, seam, etc. that the stone originates from. 

There are many veins, there are many seams, and there are many names. What is important to know, first, is this; while the name of the vein might be more important than the name of the mine, it’s not always as important as some people make it out to be. I’m talking in a practical sense here, for someone using the stone to sharpen a knife, razor, kanna blade or any tool really. A collector will view things differently; they have different aesthetics to be concerned with. 

So, there’s a basic breakdown of veins that many people talk about – for example, we see the name ‘Tomae’ quite often. Tomae is one stratum, within which there are many seams, 45 or 48 of them or something like that. So – if you know your stone is a ‘Tomae’ stone, you only know part of the story. 

Another consideration here is that, in Japan, there are several locations where stones are/were quarried. The stones quarried in Kyushu are not from the same bunches of layers that the Toishi from the Narutaki region are taken from. Many hones from the currently operational quarry known as Mauroyama are not from the ‘family’ of stones found in Narutaki either, but some are. 

The reason for this is that there are several large bands of stone running through the earths crust, formed from deposits at the bottom of the ocean long ago. The earth moves, and it did move a lot in this scenario. The original layers were once near where modern day Hawaii is located, and after the Earth shake rattled and rolled a good bit, those layers wound up where they reside today. 

When considering these layers, we also have to remember that the Earth is not a layer cake in a bakery. These layers, or strata, bend, twist, dive and rise, turn and undulate radically in the Earth’s crust. What this means is that a stone taken from ‘surface visible ‘ Tomae layer in one location could very well be from the same ‘vein’ that is only accessible from a very deep mine somewhere else. 

All this, and a whole lot more, factor into the reality of any stone in question. While certain similarities amongst stones from any one vein can possibly be realized, that doesn’t mean every stone in that vein is identical. The make up of these Jnats, many of which are considered to be siliceous shale, classifies them as, technically, a sedimentary stone. Heat and pressure are the catalysts that nature used to form these stones and those variables change at different depths. 

So – we have to be realistic when considering the weight we give to the name of the strata. As it always is, each stone stands on its own, the name is, somewhat, irrelevant most of the time. There are great Tomae stones for razors, that might not be great for Kanna blades, and there are Tomae stones that are bad for Kanna that might be good for razors. One Tomae can be hard, another soft, and yet another might be loaded with inclusions. The only way to judge any stone is by using it extensively and proving it through practical application. 

Try to imaging that subterranean Japan is made up of several different layer-cake type formations that run all over the place; sometimes the entirety of their ‘mother’ formation runs into another parent band of stone, or it dives above or below it – sometimes they’re very far apart and never come close to one another. 

The stones that are most favored, or known, sought after, etc., are those from a band, or parent formation of layers that has been referenced as making up the Hon Kuchi Naori. The most famous location for these stones is around Kyoto, and it’s often referred to as the Narutaki district.  That district is a large vicinity, and it should not be confused with the official ‘Narutaki’ quarry, which was located within that district. Within that big fat layer cake of stones, there are ‘preferred’ regions where stones were said to be ‘best’ or ‘better’ than stones from the other side of the tracks. Think of it as ‘east’ and ‘west’ locations. For example – Nakayama is an ‘Eastern Mine’ and Ohira is a ‘Western Mine’ – chances are that you’ll see more favoritism for, and higher prices on, Nakayama stones than those from Ohira. Yet – in actual use, I’d bet that the ‘best quality’ stones from both of those mines would perform equally at any task. One person may prefer one stone over another though – so subjectivity comes into play pretty heavily here. 

So – what are the names of the layers?

Starting at the top, or most shallow according to their original formation, followed by the number of ‘seams’ within the ‘stratum’. I’ll add some information that I’ve experienced from using stones from those layers also. 

Akapin - 赤ピン

Shallow layers, softer stones. Many of the very common Tennen Toishi, the type found for sale in supermarkets and hardware stores, are often taken from these seams.


Tenjyou suita – 天上巣板

4 main seams including Uchigumori, nagagumori, sotogumori, and a type of Shiro (white) Suita.


Hachimai – 八枚

This strata is home to 8 seams, I have only seen this name used once, and it was on a page showing a listing for a Suita from Okudo. The name translates to 8 sheet layer, so perhaps the layers here are thin.


Senmai – 千枚

Here, there are only 2 seams, I have been blessed to have experienced a few stones from this strata, the best way to describe them is to say they were like a mash-up of Suita *& Tomae strata. 


Tomae – 戸前

48 seams, has produced a major amount of hones. Tomae is the ‘go-to’ option for Jnats, said to be the most prolific strata for producing great stones. Factually, many great stones came from here but not every Tomae stone is a big-time winner. You will find a HUGE variation in ‘types’ and ‘qualities’ here, but overall this stratum is always going to be known as the #1 place because the ratio of good stones has always been excellent.


Gousa – this is not an official stata, it’s more of a hybrid type of situation where a seam from Aisa ‘blended’ with a seam from Tomae. The definition for this seam is somewhat nebulous, and based on assumed data. These stones are usually dark, very consistent and hard. Using this ‘name’ is always a highly subjective and easily contested judgment call.


Aisa – 合さ

4 seams, some, but not all, Karasu are known to originate from here. This is considered to be the beginning of ‘deep strata’ by many people. Like Namito, the hardness quality here is different than it is in Tomae. It’s difficult to explain, and I’ll handle that in another essay later on.


Namito - 並砥

A deep Awasedo strata with 8 seams. The hardness in this layer is a different thing than it is in the other strata. 


Hon Suita – 本巣板

Stone from this strata are highly sought after; there are a total of 6 seams, some white, some renge, some yake, etc. These stones, along with those from Shiro, were some of the most prized amongst the old-time traditional users. Collectors loved the highly patterned stones, users were most interested in the more consistent mostly white selections. These are usually hard Suita, but some are a little bit softer than one might expect. These stones are very scarce now.


Shiro suita – 白巣板 

The deepest strata in the Hon Kuchi - and there are  2 seams; they are mostly all white stone but there are subtle grey/off-white patterns in many of these stones. The most highly prized are the ‘rice cake’ or Habutae Suita, which is a very hard and very pure white Suita that cuts fast and evenly. I have not seen a soft Rice Cake Suita, but anything is possible. One thing to remember here, for both Hon and Shiro strata, is that these stones are hard, but not with the same ‘feel’ as a hard stone from Tomae – they are not usually prone to glazing or polishing up the same way, and their cutting action is very fast when compared to most hard finishing-type Awasedo. Like Hon Suita, these are extremely hard to find and very expensive when located. 

Some expanded explanations….

When viewing or referring to the list above, there are a several very important considerations to keep in mind. First and foremost – this list above is a guide that I’ve accumulated over the years. Similar info can be found elsewhere on the Internet, and you may find differing opinions also. Because this is just a list, and not a recipe with which one can refer to as a 100% absolute shortcut to select the best stone in the world, it should be viewed as a very basic overview and nothing else. 

A stone from Namito Stratum may, or may not, be ‘better for you’ than one from Tomae. Karasu stones do not all come from Aisa, but some do, and they are not ‘better’ than those from – say, Tomae Strata. Knowing that a stone is from deeper stratum does not infer that is harder, finer or coarser in an absolute sense. Karasu from Aisa, or wherever, can be hard or soft, some might scratch and others will be silky smooth.   

Geology is a complicated science, and stones change radically during their formation. Pressure and heat is different at different depths and they cause different particles and crystals to form in different shapes and sizes.  Typically, with increased, or extended periods of, heat during formation, the grain size in stones will increase. Shale forms from some type of mud or silt-stone. As the sedimentary & metamorphic process brings on increased heat and pressure – slate will form out of the shale. If this process continues – we get phyllite & schists, and further ‘processing’ will yield gneiss.   

When all the chemistry in the parent deposit is correct, and we have what is called a ‘preferred orientation’ of different particle types, along with pressure, heat – etc., the parent stone turns into shale. Mica is formed, but, in shale and slate, those crystals are not usually seen by the naked eye. When you get to the next phases of lithification and metamorphosis, the mica crystalss that have precipitated out of the parent stone’s chemistry will become visible. 

During the post mud/silt stone and pre ‘slate’ phase of this process, is when many of our favored Jnats are born. I’m referring to the finishing stone class here. Obviously, a great many types of stone came out of the ground in Japan; for the sake of simplicity I’m focusing on the typical ‘Honzan’ or Awasedo.   

The overall ‘quality’ of the stone though, is due only in part to the process of metamorphosis or lithification; an equal, and perhaps greater component – is the quality, or components within the parent stone. Our Jnats were first formed by millions of layers of tiny creatures called Radiolaria falling to the ocean’s floor, along with plant life, iron oxides, and anything else that happened to be sinking to the bottom of the sea. The Calm waters of that time frame allowed layered deposits to form, which produced, eventually, some very nice beds of shale for us to use as hones. 

Ok – enough geology. If I goofed somewhere up above, please excuse my error, I only meant that science lesson to be a precursor to what follows. 

Because our Jnats formed from many layers of organic goop that were smashed up, twisted, baked, compressed and squeezed into submission over millions of years, we can’t possibly say that any one stone from any one layer is an absolute reference to the rest of the stones coming from that layer. In any group, layer, type, strata or whatever, you are going to find variations in qualities. You are also going to find stones from multiple strata that can work, seemingly identically, for any given task. 

Additionally, it’s impossible to say with any authority, something like ‘a stone from Namito will bring on a pearly haze, where a stone from Tomae will bring up a deeper cloudy haze or only a near-mirror polish. The finial result depends on the steel, the stone, the user, etc.. It gets confusing because of techniques like using Uchiguimori to put a final polish on certain steels,  blade types - etc. But even different examples of Uchi can cause the polish to look different on the same steel. Every stone needs to be assessed on its own, after experimentation. General statements about qualities are only there for a general review – they can never ever be 100% accurate about every single stone from any layer.  


Note 1

Stones from the Suita strata are named for the eponymous Su, or ‘little holes’ found in them. These holes are formed from trapped gases there would have otherwise escaped during the stone’s formation. But – not all Suita have ‘Su’ – some have no Su and they are called ‘Sunashi’ Suita. Because they come from a Suita strata, they are considered to be Suita. Additionally, there are stones from non-Suita layers that can have Su – but they are not to be considered to be Suita; so a Tomae stone with Su is still Tomae, and it is never a Suita. Basically – the name of the stratum is always what determines the name of the stone. Renge can be beautiful, but it is not a sign of quality, whether or not the Renge itself is made up of a cutting agent has yet to be determined by any geologist, at the moment – the general consensus is that the highest quality Suita are more ‘pure’ in their coloring without any patterning -they are considered to be the most consistent stones. This is a comparison type of situation though - I have a few renge Suita that I love dearly. 


Note 2 

Some Suita are easier to identify because of their Su. Tomae stones are often called that as a catchall name for any good quality stone. Stones from Aisa and Namito are less common, and some look/feel just like Tomae, yet others are quite different in a few ways. Only the miner that pulled the stone out of the ground knew for sure what stone came from where, and possibly the wholesaler knew after the miners told him. After that – you can bet that the origin strata of many stones are anyone’s bet, and the names are then called out based on conjecture; which can be a semi/fairly-reliable method when employed by the very most educated and experienced long-term Tennen Toishi owners, users and collectors in Japan.


Note 3

The Kanji at the top of the page says Tomae Awasedo


Note 4

When you buy a Jnat, be aware that there are unscrupulous sellers that will sell an unknown stone, or one from a less known location, as one from a quarry that commands a higher price. Instead of spending blindly, and plunking down thousands on a stone from an alleged location – think twice about it. 

If you are sharpening tools, razors, etc. – the first and main concern is whether or not the stone is good quality, and what it’s condition is. The name of the mine, color, pattern, stamp, etc., is interesting information for the sake of discussion but it doesn’t reflect the stone’s qualities in an absolute sense.

To make an analogy, ask yourself if the following makes sense..

‘All Bob’s are great men. All Jennifer’s are great women’.

If it does, your name is probably Jennifer or Bob, so use different names there. 

Be smart – stop to smell the roses first. Trust me on that, it’ll pay off in the long run.

© Keith V Johnson 2014 - 2018