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Patina Question

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  • Patina Question

    I went hunting with a friend last Sunday in the same creek as the weekend before. This was his first time. Other than paying more dues, we came up with very little. However, I did pick up three pieces of chert that are approximately the same size, one I believe to be an artifact (bottom row, far right), perhaps a scrapper of some sort. What perks my interest about them is that it is obvious that all three have spent some time polishing in the creek, leaving different patinas. Two of them I believe to be of the same chert (bottom row – middle and right hand rocks). Yet, one has a darker patina and no evidence (in my opinion) that it was ever worked by man, while the other one has a much lighter patina, more like a clear coat, and it looks like every single surface was exposed recently by work of some sort (fracturing by nature or by the hand of man – especially the chipping). Assuming that the two pieces are the same chert, my question is why do two pieces of the same chert have much different patinas? My uneducated guess is that one of them has been worked recently (past few thousand years – giving it a “fresher” appearance) and the other much longer ago. I plan on fracturing the darker patina one to see if its color matches the lighter one?
    Lastly, my friend found the fourth rock that looks like a fin. It, too, is chert and I believe it is totally natural, but he asked that I post it to get your opinion on how it was formed this way ---- thanks.

  • #2
    All I see is some rocks that at varying times during its existence one side was more exposed to the elements than the other side, which caused the difference in patination. A side exposed to the sun and elements will patinate differently than the side that was buried of face down. Also rocks get bounced around and broken from the elements and the new broken face will have less patination on it than one that has set out for a long time.
    This Haraha has white patination on part of it based on it being exposed to the elements and the other part being buried. It is the same age but exposure of on one part and not the other causes a big difference.



    • #3
      That brown patination would be hard to fake :lol:. I would guess that brown (here in mo) is caused by long (months at a time) underwater exposure.
      I dont know that though, reason I guess that is there is a creek me and a buddy used to hunt (back when we had rain) anyway I hunted upstream and he hunted downstream (mile or two down) and up where I hunted it drained quicker exposing gravel bars MUCH quicker than his area which would take a couple weeks when my area takes 2 days. Long story short there would be entire bars with those brown rocks but they werent all just rocks.

      See, if that point had a fresh chip it would reveal a lighter whitish chert which is what its made of. Upstream where I hunt you cant find a dark brown rock. My explination lacks Scientific book smarts talk but if you guys go upstream you may see what I'M talking about or maybe not? My creek is just like I explained though. All those rocks in the pic got stained that brown color.


      • #4
        Interesting discussion on patina.  In the western deserts we frequently get heavy mineral deposits on upper surface. I assume from intermittent water and heat and evaporation, as well as mineral salts in soil, in addition to surface patina.  See example in my pic of rattlesnake point on in situ category posted 8-26-12.  Thanks!
        In every walk with nature one receives far more than he seeks. -John Muir


        • #5
          Lets not forget that the material that they used to make the points, is natural and imperfect in many cases. It can drastically vary in color, texture, hardness, sheen etc. which would make a difference in appearance from piece to piece, even one side to the other of a single piece of material could be a slightly different mineral composition. This along with wind,water,sun etc. wear can make any amount of the same material look totally different.