How to break up large piece of flint/chert?


MJDavis

MJDavis

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Since we do not have a subforum for Rocks, I've posted this here as my main intent is for fire.

I came into a piece of Indiana Greenstone that measures about 4x3x3 inches, and would like to break it into smaller pieces to use with steel striker and fit in a pouch/tin.

Can anyone direct me on how to do this without ending up with a bunch of tiny fragments?

I would hate to ruin this beatiful piece.

IMG_1039.jpg


Also if you have any historical/geological information on Indiana Greenstone, please feel free to offer it here.

Thanks.
 
If you know anyone with a tile saw, you can cut it up with that. I use a tile saw (diamond blade) for lapidary work (cheaper than a lapidary saw and basically the same thing), and for cutting my own flints for my black powder guns.
 
I took a piece of chert ( a lil over softball size) & put it in the hot coals of a fire, & rolled it around for a couple minutes each side, to heat it up a bit. Then waited a few hours for it to cool & hammering it a bit, it fragmented fairly decently. I did get a few smaller dime size pieces, but the others were mostly about the size of a cigarette pack laying flat, on down to the size of the top of a pack of smokes. Flakes fine & throws hot sparks. :-)

Not sure if this method would work for the type of stone you have, but it worked for me on that piece of chert.
G'Luck!
:-)
 
Wander on over to Paleo Planet and peruse their knapping forums...I bet that the answer is there somewhere.
 
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upthecreek said:
I always wack mine with a big hammer
Click to expand...

I have a piece of flint that I was trying to break up for multiple kits. I wacked it several times and only got sparks off of the hammer. I was wondering about ways to break it up too. Perhaps I need a bigger hammer??
 
the suggestion on the knapper forum is probably the best way or the saw. If you were close by a friend of mine has one he cuts obsidian with. to break bigger pieces of obsidian I use a "regular" rock(the grey smooth type :) If I can figure out a fracture point I will tap it there....wear gloves and glasses for sure.
 
How I break my knapping stone is a bit different.

I will hold it in my left hand, leather lap pad protecting my hand and I will knapp away. One or two sturdy, fast hits with a hammer stone can dislodge good sized flakes for me. If I am wanting something larger then you can take another stone on the ground and hold the chert in both hands and swing down hard. It creates a cortzian cone and snaps off a large section of stone. I do not like to use hammers because it tends to disintegrate the stone and produce TINY flakes, not large blade sized flakes.

There is a video by abo4ster describing what I just told you about slamming the chert down on another stone and snapping off a large section, I just can not find the video.

Hope this helps, horrible at explaining how I do it.

-Brandon
 
I do think a hammer stone and not a hammer would be easier. I have tried both(no expert here) and am not as accurate with the hammer...it seems to be too hard when you hit the chert whereas the stone is softer and it breaks more where you want it to.
 
Hi, new to the group here.

Since minerals are in my background I'll share a simple means to break larger rock down to any size your after. We use a hydraulic press with a thick shortened chisel mounted under the jack. Some 2X 4's to hold the rock, safety glasses and just press it until it cracks. Doing it that way you control the size, you don't destroy the specimen by bashing it and you don't create a shrapnel hazard. Learned my lesson with a 20lb sledge hammer splitting boulders to collect specimens. Got a nice piece hit me in the leg. But that's another story :rolleyes:

Be safe!
 
scorpiomoon63 said:
Hi, new to the group here.

Since minerals are in my background I'll share a simple means to break larger rock down to any size your after. We use a hydraulic press with a thick shortened chisel mounted under the jack. Some 2X 4's to hold the rock, safety glasses and just press it until it cracks. Doing it that way you control the size, you don't destroy the specimen by bashing it and you don't create a shrapnel hazard. Learned my lesson with a 20lb sledge hammer splitting boulders to collect specimens. Got a nice piece hit me in the leg. But that's another story :rolleyes:

Be safe!
Click to expand...

Good tip... Welcome to the forum!
 
oldpagan said:
If you know anyone with a tile saw, you can cut it up with that. I use a tile saw (diamond blade) for lapidary work (cheaper than a lapidary saw and basically the same thing), and for cutting my own flints for my black powder guns.
Click to expand...

I just acquired my first flint. I was able to get three decent sized flakes with good sharp edges by striking lightly with a small ball hammer. I've yet to learn flint knapping. Until I do, I don't want to take the chance of ruining these flakes by my ineptitude. Would a grindstone or a sanding belt work for keeping the edges sharp?
 
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