I purchased 40 pounds of Flintridge and most of it looks like what I remember as Flintridge chert. One rock has fine lines in it so I slabbed this rock. What do you guys think? Does this look like Flintridge chert? Have you seen rock like this before?
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Flintridge???
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Pretty stuff No wonder it is Ohio's Official gemstone. http://geosurvey.ohiodnr.gov/portals...ation/el06.pdfTN formerly CT Visit our store http://stores.arrowheads.com/store.p...m-Trading-Post
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That is a variety of Flintridge flint known as Nethers. Its outcropping is on the Nethers farm which is where it gets its name from. Although it isn't quite as abundant as typical Flintridge I have found pieces of it through the years. I think its classified as Flintridge because its outcropping is so close to the main outcropping of Flintridge that we are all familiar with.
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Yes, that should really bring out the colors as well as the other 40 lbs. of Flintridge. Here is a link to heat treated Flintridge that was knapped by Roy Miller. Roy actually purchased land where it outcrops and collects the material and works it.
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Thanks again guys. I did an internet search of the Nethers farm and quarry. I found some interesting info. There was an ancient quarry there and people can still dig chert there. I would love to go there some day and dig my own rock.Michigan Yooper
If You Don’t Stand for Something, You’ll Fall for Anything
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Hi Ron... commenting on some of the above and in reply to your PM. It does look like material from the Nethers quarry, and that would be regarded as part of the Flint Ridge formations. As you will see from some of the pics in that linked pdf, there isn't really any such thing as "typical" Flint Ridge pattern or colouration. There's huge variation from exposure to exposure and some of the more exotic forms occur in small quantities with no specific name attached to them. The Nethers material which has closely banded two-tone grey coloration is generally referred to by modern knappers as "Nethers pinstripe".
Some banded cherts have differential degrees of silicification, such that you may get step-fracturing at the boundaries when knapping. Examination with a decent loupe (or some experimental knapping) will soon establish if that's the case.I keep six honest serving-men (they taught me all I knew); Their names are What and Why and When and How and Where and Who.
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Thanks Roger, I don't know how this rock pattern was formed but it appears that the black streaks come from a large black area in the stone.
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That may well be so. These are not sedimentary bands as you might see in limestone for example and also not concretionary rings as you get when material has progressively grown from a nucleus. The general geological consensus is that they are effectively “stress” features created by compression from overlying material during lithification which results in the silica crystallising in different ways in the stressed zones. There is a point during the petrogenesis cycle when the silica from which flints and cherts are formed is in an oozy gel-like state. Pressure from above and around can induce it to flow in bands and/or cause impurities to creep into it in a series of diffused lines. Often, when the bands are dark, they’re hematitic and it’s quite possible that darker area is iron-rich and has provided the iron for hematite impurities to give it the colouration.
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Thanks Roger, That all makes good sense. I suspected that the black was high iron content. There's even some rust color in the rock. Probably a couple of different iron oxides there.
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yup thats Nethers alright
i have some it s nice stuff
i never heated it,maybe thats why it was so tough
Roger is absolutely right about getting step fractures on he boundaries of some of the multi colored chertseven after heat treating them this will happen and you just have to learn what each different color wants as far as platform,force etc
and when you try running a flake where the color changed down in the area the intended flake is to run,thats real fun to figure out
ifn you would like to sell a slab or two let me know,ive got some one whos interested
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Now how did I miss those question marks. Maybe because I was looking at Greg's post just prior to this post or the post about the missing links . STill looks like real pretty stuff Ron Nethers or not! LOL Just kidding,
This is great information guys, thanks to you all for making this site great!TN formerly CT Visit our store http://stores.arrowheads.com/store.p...m-Trading-Post
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