Author Topic: Discussion Of Burlington Chert  (Read 11471 times)

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Ahnlaashock

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Discussion Of Burlington Chert
« on: January 03, 2014, 05:28:00 am »
I am a beginner, even tho I am an experienced lapidary.  I started trying to learn how to make simple tools, the way they did, from available local resources.  I knew there was a local chert in sizable pieces, and that has since been identified as Burlington. 
Everyone says Burlington, like it means one thing.  Well, that isn't how it is here.  I have brown grainy material, all the way to agate like translucent material.  Heck, I even have a piece with a barber pole swirl.  I have several grades of Burlington, that do not require any kind of treatment to knap well and easily.   The best is almost as easy to work as good true flint, and only obsidian has been easier to work for me. 
I can post photos of the various grades I have so far encountered, if needed. 
The very best working material so far, is a glassy banded/swirly pure white to gray material.  It compares very well with many lapidary materials.  It even fractures to a smooth shiny surface, time after time.  You can push flakes on it raw with a pressure tool.  Unfortunately, the piece I found was float, and badly fractured.  The material appears in the creek over a wide area, but it is all in small pieces, about golf ball size.  It patinas white or banded.  The piece I worked was from near the top of a ridge, in a very steep valley.  The top layer was this pure material, but the other parts of the same core were much courser grained and hard to work even with hammer stones.   The finer material compares favorably with many agates or fine lapidary materials, and would make a fine polished piece also.  So far, it is not translucent, but instead is of a solid color, although it may be swirled or banded.   Many of the fine grained smaller pieces appear to be a solid gray inside if struck, even if they were banded in the patina.  Some of this material is translucent.  If you are used to working with tough stone, you will hit this one too hard in the beginning.  Brushing up the edges makes flakes rain like crazy, it can be worked all the way to pressure stage, using antler billets, and one of my billets is a whitetail tine.  Both ends can be swung to work the better material.  Oddly enough, the tine billet tends to knock almost hollow ground edges when used. 
I also found limited quantities of a darker gray material that does things like produce three inch flat flakes, but so far, that supply is very limited. 
I even found a version that has sparkles all throughout the material, making it look like it has glitter inside the stone.  It works okay, but the edges are not as sharp as the more solid material.   It appears to be small crystals locked together in a matrix when you start to work it.  For jewelry use, it might make perfect points, but for actual use, it isn't sharp enough or tough enough. 
So far, here in northern Jefferson County, the material is mostly the gray stuff that leaves a grainy pebbled surface on flake scars.  I found one deposit of a much finer grained material in large pieces.  I posted a picture of it in the Jefferson County Chert thread.  It is also not translucent.  There is a much finer grained gray material that is hidden under a variety of patinas that is common here also.  It is very hard to work without treatment of some kind.  Some of this material is translucent.   It is just hard and tough.
The much better material I was talking about, is from Washington County for the most part.  I have found a white material that may or may not be banded, and may or may not be workable there.  The very best being this incredible material I have been bragging about, and the worst is thin layers with layers of concrete in between each. 
There is a gray material found in larger pieces, with the patina we recognize as Meramec cobble here in this area.  It is often in layers also, and is often badly twisted and uneven.  Good layers can be worked pretty easy, but I don't know about flaking with pressure or not.  Why one forms the brown patina, and the other forms a white or banded patina, is not evident from the material itself.  Inside, a flake from each can be confused with each other.
So, when you say Burlington, as so many do, are you describing one certain type of Burlington, or are you discussing it in general?  I am not sure the spread of material I have found, even in this short time period of searching, fits under one name or variety. 
Describe what you call Burlington, please! 

Offline Dalton Knapper

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Re: Discussion Of Burlington Chert
« Reply #1 on: January 03, 2014, 07:55:03 pm »
There could be other rock present besides Burlington Chert. What you have to realize is that you are talking about rock formations within a geological area that could be mixed with other eroded strata from earlier periods unless you find the rock in a formation that can be identified. Being familiar with lapidary, you should know that Jade for example can be quite varied. Well, so can chert. Perhaps you are finding different rocks and some Burlington as well. 

Novaculite can be anything from a sandstone like texture (which the whetstone industry loves) to something that looks much like a chalcedony and is translucent. It's all about geology.

This shows some variety in Burlington: http://www.uiowa.edu/~osa/lithics/drawers/OutOfState/DrawerLGImages/Drawer8Images.html

Ahnlaashock

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Re: Discussion Of Burlington Chert
« Reply #2 on: January 03, 2014, 11:24:31 pm »
While there may be the odd rock that is not Burlington, most of it is.  I have seen examples of the various types or grades being part of the same piece, as with the best I have found.  It was the top layer, and what was under it would have been like working quartzite.  I spent the last two days spalling and removing flaw from the pieces I collected here close to home. 
It runs from very course, almost quartzite textured, or even larger crystals that sparkle in some samples, to glassy and translucent.  From solid color to banded to layered.  From pure white, to dark gray. 
I was watching a video, and the person said that the stone they were working, was a lot like working Burlington.  That kind of threw me, since what that means, is you pick up each piece and see how hard you have to hit this specimen.  The strikes used to spall the last piece, might completely shatter this chunk, or may not even bother it at all. 
Making blade or flake functional tools is no problem, but i still can not push a flake at all.  That is why I am going to heat treat a batch.  I am keeping plenty as is.  I still plan to learn how to work it fully raw also.   I took a picture of the stuff I am cleaning up right now, with flakes of the other grades mixed in.  Heck, there is even one of my pitiful blade points, or a partial anyway.  It sits on similar material.   It is all the same material, and seems to basically be different grades.   The glassy chunks might have been heated in nature, but they are a class way above any of the others.   I just have not yet found large chunks of that material that is not already fractured badly.  In the creek, it averages about golf ball size chunks.   I did not have any of the brown handy.  The big spall is right at 6 inches. 

Offline iowabow

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Re: Discussion Of Burlington Chert
« Reply #3 on: January 04, 2014, 07:26:39 am »
Go to the university of Iowa and down load the geological survey. I live just outside of Burlington Iowa and  the formation is named after this area. That survey will explain in detail what Burlington is.
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Offline iowabow

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Offline caveman2533

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Re: Discussion Of Burlington Chert
« Reply #6 on: January 04, 2014, 09:32:43 am »
You may have some harvester chert also. It tends to be dryer, not as silicified and will often have concentric rings like your picture, and is more nodular.. Again tho check your geological reports for formations locations.

Stringman

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Re: Discussion Of Burlington Chert
« Reply #7 on: January 04, 2014, 10:13:59 am »
That looks more like harvester than Burlington, but I'm sure the 2 are closely associated.

Offline iowabow

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Re: Discussion Of Burlington Chert
« Reply #8 on: January 04, 2014, 12:22:32 pm »
Use this with the pdf and you should find the answer you are looking for.
http://www.uiowa.edu/~osa/lithics/drawers/OutOfState/DrawerLGImages/Drawer8Images.html
(:::.) The ABO path is a new frontier to the past!

Offline iowabow

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Re: Discussion Of Burlington Chert
« Reply #9 on: January 04, 2014, 12:35:37 pm »
(:::.) The ABO path is a new frontier to the past!

Ahnlaashock

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Re: Discussion Of Burlington Chert
« Reply #10 on: January 04, 2014, 01:15:43 pm »
Thank You! 
I will comment when I have read the information you provided for me!   

One of the more interesting chunks is still not broken down.  It was the only solid piece of the four.  I only knocked off enough to make sure of the material. 
In the case of those four chunks, root heave and the expanding trunk had pushed them out of the ground around the base of a Black Oak. 
Anyway, I will say more when I have examined the information you provided!  Thank You very much! 

Ahnlaashock

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Re: Discussion Of Burlington Chert
« Reply #11 on: January 04, 2014, 05:21:43 pm »
There is not a lot there that I have not already looked at.  The sample pictures are more confusing than helpful. 
The large plate I posted a picture of in the Jefferson County Chert thread, could easily be used as an example of either Harvester or Burlington, and the fine stuff could easily be called Jefferson City, but I took it off the top of a chunk of Burlington with my own hands, while I was studying the distribution of the various grades by elevation. 
In that location, the very best material is found very near the top of the ridge.  The hollow is deep and narrow, leaving a termination that is pretty much a cliff you can just walk up, on both sides and the end.  There is a layer found almost at creek level, but it is the layered material with the concrete between the layers.  There is usable material there, but you are going to work your tail off finding thick layers and then trying to remove the surrounding rock successfully.   The material just off the ridge line, is much more solid, and tends to be in larger chunks also. 
You have to remember, that in either location I am discussing, a large percentage of the soil is chert chips and shards.   Like the Mo. Department of Conservation says, it is literally as common as dirt here.   I am still not sure how they used moccasins at all in either area, since the ground itself destroys leather soles very quickly during normal use, and along a creek, a pair might not last minutes before the first time they are sliced through cleanly. 
One of the things that is becoming more and more apparent, is that the color of the material is influenced by the moisture in the stone itself.  In the picture I posted, on the top left, is a large thin chip.  When it was detached, it was a solid gray color.  As you can see from the picture, even in a short time, it is now turning white at the thin areas, brown in some thicker areas, is translucent, and appears to actually be an off white silica with lots of fine particles suspended in the matrix.  In that example, the description of silica invading voids partially filled with other debris seems to hold. 
In other examples, it does not.  I have a piece near my foot, that has a top and a bottom cortex, with the sides being faces of the vein material.  There is a central healed fracture plane that runs from one cortex to the other, at an angle through the piece.  That is not uncommon at all with this material, and neither is the difference in the material on either side of that fracture plane, in the same vein.  One side of the crack, which ran north and south in the vein, is a nice darker gray mottled material that is middle of the road quality knappable material.  Not shiny, but good and solid.  On the other side of that fracture line, it looks like granite tried to form, and an incredibly course conglomerate is found.  It isn't usable in any way, but it is even tougher than the solid material. 
The dark bulls-eye pattern was badly fractured along the length, running from the hollow it terminated in, outward for about three to four inches.   I bladed and spalled all that was possible out of it, but most of the pieces are pretty small because of the cracks.  Of the outer portions tho, I got some very good material. 
The pure translucent material flakes almost like obsidian. 

Offline iowabow

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Re: Discussion Of Burlington Chert
« Reply #12 on: January 05, 2014, 07:26:07 am »
Other than naming the flint what are your goals here?
1 . learning about rock formations
2. Heat treating
3. Flint knapping
4. Resale of material
5. Making small arrowheads
6. Making large points
7. Rock collecting
8. Trying to locate the most pure
9 trying to locate the most color
10. Trying to recover rock in the easiest way
give us an idea of were you want to go with all your questions so we can best answer them.
(:::.) The ABO path is a new frontier to the past!

Offline iowabow

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Re: Discussion Of Burlington Chert
« Reply #13 on: January 05, 2014, 07:36:44 am »
In a creek where you find flint in layers you will also find creek sort for quite some distance on the down steam side. This flint has been tested by the elements and you should find quality material to knap in the debris. You will be working with a range of different burlington type stone and galacial till.
(:::.) The ABO path is a new frontier to the past!

Ahnlaashock

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Re: Discussion Of Burlington Chert
« Reply #14 on: January 05, 2014, 06:43:24 pm »
My goals?  Good question, but I don't think I have a good answer. 
I found a blade, dug out the old collection, and started to study.   I decided to learn to make tools with available resources, as someone living by that tech would have to do in the past. 
I learned how to make blades, survival type tools, and I am working on learning to work the stone better.  I don't know where or when I will be satisfied.  I have two five gallon buckets of bifaces, preforms, plates, and chunks that are about 95 percent clean sitting next to me as I type this.  I have worked two pieces of stone this morning learning, and started an axe head that will require things I can't do inside easily, the tools being under 12 inches of snow right now outside. 
I am learning. 
I don't know where that will lead, or really care.  At this time, I have no plans to sell stone, and my skill level certainly isn't going to support anyone buying my work. 
Learning about new types of stone is something I do constantly, but this is not the kind of stone I usually work with.  The really high grade stuff would support lapidary use, and I am going to cut a stone out of it, but my focus is on learning to make tools with available resources.   I am learning another art/craft form. 
I am not looking to really replicate anything at this point, and all I have been doing is learning the techniques.  Today I worked learning how to create undercut curved scraper faces that are very strong, and have major support behind the scraper edge, making it almost impossible to damage the edge using for what it was intended.  That is easy using this material by the way. 
I tested a chunk to see that it has in it, that I knew was pretty rough material, resembling quartzite.  I think I will see what happens when I hit it with wood billets.   I compared the advice to make isolated low platforms, to another idea, using high platforms deliberately.   
I do plan to heat treat some material, and with the temps supposed to hit minus eight, I may stick a sample of each grade in the oven this evening, and run a cleaning cycle, helping the furnace along.   I would already have the other material drying in a turkey roaster, but I forgot to pick up the sand, and the car has around 13 inches of snow on it right now.   The dry inside air is already causing changes in the appearance of much of the material anyway. 
I have been a rock hound for many years, and have about 10 tons of material in buckets already.  When I cut today, I usually do picture cabochons or faceted clear gemstones.   Much of that material would likely also be appropriate if slabbed and heat treated, but I am using stone I can find in this area alone so far.  I have been hitting this stuff long enough now, that letting me anywhere near obsidian would not be good!  I have a few slabs of Rainbow sitting, that are cut about an inch thick for knapping use, but I got them for other reasons, years ago. 
 
I am just looking for a discussion about working this material, the various grades, and how others are making elaborate tools out of the raw material.   I go around 6 foot, 240, and I already know strength is not the answer.  If it was, I would be pushing flakes by now.   I begin to understand the angles with this stuff.  I understand that techniques like Jackcrafty uses allow you to overpower the materials in a very precise controlled way, but I have not figured out how to do that using straight ABO techniques.   The swung whitetail tine uses speed to power on through, and produces pretty good flakes, with either end.  This is useful up to the preform stage, but when you start needing to hit small platforms precisely, swinging really fast, naturally you are going to start having control problems.     
I am looking to learn.  Beyond that, only time will tell. 
« Last Edit: January 05, 2014, 06:49:00 pm by Ahnlaashock »