Jefferson County Missouri Chert

[Mike_H]

Yep, same stone I got.  It's either burlington or keokuk.  Not sure which.

[Ahnlaashock]

I can drive thinning flakes, and I even created an overshot that took out half the other edge today, but you have to hit it hard.  I have better control most of the time now, than when I started, but I still miss when I have to swing that hard, far too often. 
Interesting that using my antler tine pressure tool turned over and backwards, swinging it like a small billet, you can drive pretty good flakes off this material once it is pretty thin.  Then it becomes a game of if you can hit precisely.  I can't yet, but it gives me another tool to use. 
I am hoping that once I fracture a large boulder open, that I might get away from the crazy tabbing and hidden fractures. 

[caveman2533]

Looks like raw Burlington to me. It is very tough material in its raw state. 550 degrees would do wonders for it and maybe even bring out some color.

[Ahnlaashock]

After a lot of looking at pictures, watching videos, and then busting up a few hundred pounds learning the material, I tend to agree that it is what is called Burlington Chert. 
What that does not cover is the various grades and levels within the stone itself. 
This material comes in grades with almost a compacted clay type texture, that does not break to as fine of an edge, and the edges wear quickly, all the way to edges almost equal to obsidian, that are translucent.  It runs from almost blue, to gray, to pure white in color, all of which work differently.  Some pieces have almost a flow grain to them, where the angles produce different results from side to side/direction.  Almost all pieces exhibit the healed fracture lines, although they may be well hidden until revealed by a flake ending at that point.   Sometimes even if they are there, the flakes travel across them anyway.  It runs from almost glassy, all the way to the compacted clay texture.  In the darker material, it is common for a flake scar to have an orange peal effect. 
It isn't different material either, since I can reach down right now and pick up a football sized piece that exhibits both the gray and the white, on the same piece. 
Years back, a friend that used to do gem shows with me, gave me a piece of Burlington, that he was using to demonstrate at the show.  It is almost pure looking off white, and I reduced it to a pretty thin preform using a tine billet and percussion alone in minutes after I found it.  I am assuming this is the difference between heat treating and not.  If this stuff worked like that piece did, I could make things no problem, with the tools I already have. 
I am collecting enough good solid pieces with most of the junk already removed, and I am going to cook a batch as soon as I get enough good pieces to fill the roaster.  I have the ability to take it all the way to white hot, and to slow cool it, but the other stone I tried that with, was weakened to the point it crumbled. 

[caveman2533]

550 should be plenty of heat. If you can soak it at that temp it will help bring out color. Pure white material may stay white or pink up a little. If you have material with shades of blues and tans in it it will color up to darker pinks and reds. The tans may darken also.  If you are heating big chunks take the temp up very slowly My recommendation would be to reduce it to bifaces or spalls 3/4 inch or less in thickness.

[Dalton Knapper]

Listen to Caveman. It is Burlington (I could have told you that based on geography alone) and it will be nice stuff if heat treated properly.

[Ahnlaashock]

I am listening.  I just have to do things myself to fully learn.

I was hoping that heating it might open some of the healed fractures, allowing a little better ability to reduce it to useful bifaces, if that makes sense.  Collecting useful reduced pieces is the stage I am at, but I was hoping to be able to heat some of the larger pieces first.   
It might be the material I have here is more prone to the healed fractures, than other veins or sources.  So far I have not gone more than about 150 yards from my front door.   I am sure there is better material out there.  I know where there is about a five hundred pound boulder, but have absolutely no idea how to produce large spalls off of it yet.  It looks to have a thick layer of good material, but the gray material is simply tough to spall.  I watched a video of producing bifaces with a dogwood billet and a wood mallet, but I have yet to find material that good, at least that large.   Still hoping to find a large piece of the white material that breaks to such a nice edge, with such smooth scars, that is not full of cracks. 

[Ahnlaashock]

I had it wrong!  I did not need to go farther afield looking for better material.  I needed to look close to home. 
I spotted a likely looking chunk while walking to where I stopped looking before, about 100 feet away from my front door.  Turned out to be four 100 pound plus pieces of a thick vein.  Even better, it had been exposed long enough for it to fracture into platters, blades, and what are almost slabs.  A little tapping with a large hammerstone, and the cracks opened right up, allowing me to reduce much of it to clean crack free material that is all very nice, but some of it could almost be called agate.  It is approaching lapidary grade.  It is banded and has orbicular patterns.  Several large platters have bulls-eyes, and I even recovered one piece with colored banding and a bulls-eye.   
I don't think any of the material I had found before will make it into the first batch to be heat treated!  What I recovered today is simply much much better material, and I think I could fill two roasters with the material already broken down into usable bladed forms.  There is a piece that is about 15 pounds sitting by my foot, that is pure, banded, and so fine that by rights, I should slab it into about three platters an inch thick. 
This material works better also, so I may try a piece of it raw. 

[caveman2533]

Now you are making me jealous. When you load the roaster put the thinnest pieces in the corners and the thicker pieces along the sides and to the center. I used to use play sand as a buffer . It helps slow the heat spread thru the material and buff any cool air it may receive. Put about an inch or so in the roaster with Pan removed and the I would layer or stand pieces in the sand, covering as you go. only use sand to fill the spaces. Pack it as tight as you can. In my kiln I would hold it at 200 for 24 hrs then ramp up to 550 and hold for 8 to 12 more then ramp it down also.  If you go to Home depot or Walmart you can get thermometers used for turkey frying. Put on in a corner and Drill a hole thru the lid or stick it thru the vent on top and into the sand. This way you can monitor temps with out opening the lid. Wait until it is about 150 to open it. Good luck and show us some pics when its done.  I"d actually like to see some before you roast it.

[Ahnlaashock]

Here are a couple of quick pictures.  It is too cold out there to do more right now, and the camera fogs up.

The pile. 


A solid piece of pretty good material with some white banding near one end. 


A little piece of the banded material.  Too cold to search for more in the dark.  I was playing with this piece, just seeing how it works.  It can be worked raw, but I don't know about pretty flake patterns and such.  It is a lot easier to work than the run of the mill gray stuff is.  Anyway,


A lot of it is still in pieces that may be too large, but I did the easy reduction only.  With it cracked and bladed the way it is, that seemed to be best.  There is a lot of material in some of those big chunks yet.  I preformed a piece out of one of the thinner tabs, and it worked pretty good, comparatively.  The one side flattened easily, and the other side hinged all the way around, leaving a hump I have to figure out how to undercut.  I was using an antler tine billet, swinging it hard and fast to do the reduction.  If you want a flake to run all the way across, or take out a central problem, you still have to hit it like you are mad at it, and need to switch to an appropriate hammerstone or implement.  It will flake using less force, but it runs a quarter inch and hinges.  Most I have played with until now, was very hard to work just swinging the light tine.  This, someone very accurate swinging a tine billet like I am doing, could do everything but the final edge work. 
The pile in the house, in the very dry winter furnace air all the time, is starting to turn white, I am assuming as it loses moisture content.  With these pieces being as large as some of them are, I am wondering if I should add a day or two onto the drying stage, or if I should simply move them all inside into the dry air for a couple of weeks.