Primordial Rock. Kimberley Western Australia

Discussion in 'Hones/Honing' started by Ozziedoc, Aug 2, 2015.

    $DSC03289.jpg $DSC03290.jpg

    I've been sharpening knives for a long time and have amassed a good collection of synthetic stones, diamond hones and ceramics and even used the scary sharp technique with wet and dry and films. However my experience with natural stones has been limited to a couple of small pieces of Arkansas from an old Buck kit.

    Embarking on a straight razor adventure I have purchased some large Arkansas stones but have yet to prepare them.

    While researching natural stones I tried to make some sense of the difference between Arkansas, Jnat and coticules.

    Part of that reading was the chemistry/geology of those stones. I was struck by the similarities between some of the well known naturals (SiO2 in a Sericite matrix) and Zebra Rock from the East Kimberley region of Western Australia.

    Of course chemical composition doesn't define what makes a good whetstone.

    I happen to have a good friend who made a tree change (Professor of Biochemistry) a few years ago and bought the Zebra Rock Gallery in Kununarra WA which is why I thought to check on his offerings.

    Zebra Rock is sedimentary siltstone as is Arkansas and Jnat stone. Zebra Rock is 600-700 million years old but a variation of that is known as Primordial Rock and that is dated around 1200 million years old.

    In contrast Jnat is 70 million years old and Arkansas is 350 million years old.

    It is found only in the East Kimberley region near the famous Argyle diamond mine. Very few mines now operate because large swathes of that region were inundated when the Ord River was dammed creating the huge Lake Argyle.

    The stones as far as I know have only been used for decorative purposes but I prevailed upon Bruce to cut me a few slabs to try as whetstones.

    There are over 50 colour variations recorded and ones shown above are grey and brown/cream. The second image is the underside of the brown stone.

    There is no grading system in place and no previous reported use as a whetstone and many of the names are just for marketing purposes so I had no idea how they were going to perform. The only other fact that seemed relevant was a report that primordial has a grit range of 14000 or higher.

    As mentioned in another thread the grey arrived broken and I have yet to fix that but I have tried the brown/cream as is with no lapping or other preparation.

    I took some kitchen knives that have previously been sharpened using a ceramic stone which left the edge with obvious striations and proceeded to slowly hone. A nice slurry developed over some time and I ended up with a more than adequately sharp knife. Examination of the edge under a jewellers loupe showed a highly polished finish, much much better than I have achieved with 2000 grit W&D.

    Not only that, the feel of the steel on the hone was unlike anything I haver experienced using any of my previous stones. Keep in mind that I have never seen a Jnat or coticule much less handled one so I have no comparison base but if they perform in any way like this I understand the passion.

    There are members here who are not only passionate but have a tremendous knowledge base and who would be much better qualified to assess the qualities of this stone.

    If anyone would like to review the brown/cream one I will send it to them. I'm not sure how I will choose if lots of you want it but we'll work something out.

    For those that are interested, here is where I got it from and my disclaimer; I have absolutely no financial interest in this.

    http://www.zebrarock.biz/default.html
     
  1. Interesting. I"m in for a test.


    Arkansas stones and Jnats are not siltstones. One is shale/slate - the other is a type of Chert.

    The initial formation of Jnats began longer than 700 million years ago. I 'think' we're talking 'billions' of years ago there.
    The thing is that the process of lithification is slow, so - at one point down the road those early deposits became Shale, which happens millions/billions of years after the first deposits settle. Siltsone is an early formation in any sedimentary bed. So - comparing age of siltstone to age of shale isn't a linear concept. The initial deposits that formed the shale may actually be older than the deposits that formed the siltstone.
     
  2. Interesting. And there is a lot of that rock?
     
  3. I would also join the test if youre interested in other opinions....
     
  4. "Abo Strata"
     
  5. No and it seems that the few operating mines will be inundated as the Ord River scheme progresses.
     
  6. PM sent.

    The information on age and geology/chemistry was gleaned from several websites and I don't pretend to be an expert especially when it comes to lithification and rock metamorphosis. 70 million years is a looonnnggg time though.
     
  7. PM sent.
     
  8. Interesting indeed! I think it would be nice to see microscopic results of the scratch pattern and or polishing effect.

    Again remembering that natural stones quality very from stone to stone.
     
  9. I have forwarded these rocks to a couple of resident experts and am looking forward to their reviews.
     
  10. Got Ozziedocs Stone yesterday...just a wonderful looking stone!! Interesting is that there are so many different colorations and patterns on the stones....

    I will later do a evaluation if the stone performs in a way to be usable for honing straights...

    The first thing i experienced with this stone is that it drinks water like a Camel...i did a short vid to show whats happening on the surface when water is standing on the surface...

    I already might have a clue that this mateial ive for testing might not be usable as a water stone...it just soaks water to fast !

    I will try the stone under running water, with a glycerine Water Mixture and probably with oil later....

    So more results will follow ;-)

    I did a Video of the soaking, you can find it in my Youtube Channel...
     
    Last edited: Aug 13, 2015
  11. First - I want to send the OP a huge Thank You! for sending me these stones to check out.

    The stones arrived today. Very interesting stuff here.
    Both seemed like siltstones - and that turned out to be correct. One thing though - the Zebrastone is way porous where the Primordial is way less thirsty. By feel - the Zebra did not strike me as a contender, and that is how it proved out in my very basic tests. The Primordial though, showed some promise - but not as a finisher. This is more like a mid-range stone to me, it's fairly effectivve and it seems usable. The scratch patterns tell me the white side is coarser, around 5/6k or so, where the red side seems to pushe up a bit higher, possibly to 8k if I'm working it.
    I'm relating to JIS standard stones here.
    Now - my 8k JIS synthetic stones are way finer and more consistent, same for Coticules, TOS, and Dalmores.

    The Primordial is nice, useable, but not something I'd go looking for unless I wanted a different flavor in the box. If I was out in the middle of nowhere without my regular hones and someone passed me a Primordial, I could get a working edge off of it.
     
  12. Here are some pics of the stone...till now i can confirm what Keith already mentioned...there seems no real action honing on the stone...there ist no metal swarf coming up...looking forward if anything happens with water/glycerine or under running water...

    [​IMG]

    [​IMG]

    [​IMG]
     
    Last edited: Aug 15, 2015
  13. ouch

    ouch Moderator Emeritus

    I find that those 1.2 billion year old rocks benefit from a few month's worth of additional aging in my hone cellar.
     
  14. Send me your address.
     
  15. Thanks for the honest appraisals Gamma and Doorsch.

    As I said I only tried the brown/cream stone on kitchen type knives and found it very satisfactory for that purpose. I didn't try the grey stone at all before I sent them off to the razor hone experts.

    The stones have only ever been marketed for decorative purposes and as far as I know nobody has tried any sort of grading system of the many types available for use as sharpening stones.

    Given the easy availablity of consistent synthetics and the relative rarity of these stones this is unlikely to happen in the future if they are not showing an advantage over other well documented natural stones.

    But hey, this is fun and they are beautiful stones.
     
  16. Dcaddo

    Dcaddo Moderator

    Never know until you try.
    And I agree they're very pretty stones.
     
  17. Another Update on the stone i got for testing...i did two tests yesterday...

    To prevent soaking i used glycerine on the stone....funny thing also the glycerine got soaked in after a certain time....

    I first used a razor which needed a touch up...i did a lot of laps, nothing really happened optical, but the HHT was better then before this test, so my idea was that the stone might be a very very slow stone...

    So i reset the Bevel on a DMT600 on a Gold Dollar Razor....i wanted also to bring a bit more spressure on the stone to see if this creates any different behavior....

    Using the glycerine with only a bit water it was possible to work on the stone...the stone drinks everything it can get away ;-)

    I did around 300-400laps in total...until i had the feeling that an optical change of the bevel was created...

    To bevel looked more polished and scratches have been removed...

    Then i stropped and did a Hairtest, well it worked but not consistent enough. After stropping it was possible to shave off arm and leg hair without any issues. A microchipping was left due the usage of the DMT...so not really a well formed bevel...

    I will risk a testshave this week...so it seems that also with this stone something is happening after a long time...but i also think its not really a usable Razor Hone...just due the huge amount of laps which have to be done...
     
    Last edited: Aug 17, 2015

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