Identifying knappable rocks

Shotgun

Shotgun

Joined
Feb 3, 2006
Messages
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I'm interested in knapping but was wondering how to identify rocks I can use in the wild. The closest thing I can come up with in my search is "Just smack it and see what happens." Is that how you guys do it? I'd really like to be able to see it and know what I'm looking at.
As an aside, my interest isn't in points necessarily but in making useable edges for stryking steel, game prep, etc. Simple knapping in other words.
 
Ah, I would also like to know. Funny thing is that three of my closest friends are geology majors :D I'll have to ask them tomorrow :)
 
You're doing it right. Unless you already have an identified outcropping of stone, you really cannot tell what a stone really is until you "whack" it to see the insides and how it cleaves. This is the first step in geological stone identification: crack it and see the insides.

The worn exterior of most stones is not a good indicator of what the actual composition is.
 
I look for signs of concave fractures.

Of course, as others have stated, concave fractures might not be visible on well weathered rocks, but even a weathered concave area is a good indicator.




Big Mike

”Scaring the tree huggers.”

Forest & Stream
 
I have friends that knap. I don't, but I have asked for shards for flint and steel in the past. If you handle the shards, and roll them together they have a clink to them. It's kind of like striking an axe to hear the ping for the hardness. Sometimes with gravel type rock you can kick them and hear the sound of the rocks that you can break to get a sharp edge. Chert around here.
 
Big Mike said:
I look for signs of concave fractures.

Of course, as others have stated, concave fractures might not be visible on well weathered rocks, but even a weathered concave area is a good indicator.




Big Mike

”Scaring the tree huggers.”

Forest & Stream
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This is a good tip. From Snake Dr's link to chert, you're looking for the conchoidal fractures in the face of the rock. Very cool.
 
i live in and around an abundance of indian artifacts. we find ryolite (sp too lazy to look it up right now) in black and green.. mainly black.. they are easy to spot. hell we have mtns of this stuff within miles of our area.. huge mining areas for native americans.
 
hung-solo said:
i live in and around an abundance of indian artifacts. we find ryolite (sp too lazy to look it up right now) in black and green.. mainly black.. they are easy to spot. hell we have mtns of this stuff within miles of our area.. huge mining areas for native americans.
Click to expand...


What part of NC are you in?
 
As previously mentioned "glass-like"

The easiest way to identify a rock with high glass content is to hit against another rock. The higher the pitch (sound), the higher the glass content. That will get you started.

Flint knapping ~ so easy a caveman could do it!
 
for practice i use "johnstone," old toilets, tv and comp screen glass.... i found a mess of chert on my last hog hunt, but i have not heat treated it yet, but just as i was running low on glass my t.v. broke... silver lining.. lol.... u can see some pics of me knapping tv glass in the outdoor pic thread... find iont stone is the first step... paleo planet is a great place and has awesome tutorials....
 
Funny story.... when my wife and I were looking at the property we have now, before we bought it, it was brought to our attention that lots of artifacts had been found here. They were made from various flints.

We took an extended walk around the property, including down into a seasonal stream bed. As I have a tendency to over-value my own knowledge base, I proclaimed that the artifacts found on the property "must have been brought here from somewhere else, as the stones on the property are not flint."

I said this with a great deal of certainty.

My wife, who is well accustomed to my tendency, leaned over, picked up two nicely rounded, nondescript pieces of river rock, struck them together and fractured one of them, exposing a very nice view of very acceptably flint.

"How's this for some quality not-flint?" she asked me, with a big grin. As happens sometimes, I ate crow. We have lots of flint on our property. I just ain't no geologist!

Andy
 
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