Couple of artifacts found in creek and a rock ID question

[bowtarist]

Here are atleast two pieces I've found in the creek.  The one on the right actually has some type of geode or crystal in it.  The question I have is, does anyone know if the other rocks here are knappable?  There is a good supply in the creek here if I look for it.  It seems "glassy", but it is sorta like crionoid hash, like a lot of crionoids compresses, really compressed and slick, hard looking.  I've wanted to try to heat some and hit it w/ a billet, but don't really know where to start.  I've only knapped glass,

[JackCrafty]

It looks a little tough.  Try using a copper billet on them.  Or use a steel rod (rounded on the end) to knock off a few flakes.  You'll know pretty quick if it's any good.

[bowtarist]

How about heating it?  Make any difference?

[JackCrafty]

Heating makes a lot of difference in some rocks.  Dry the rocks in a toaster oven at 250 degrees for a few days.   Then heat to 350 degrees for a few hours and then let it cool down.  Take a few flakes off to see if it's glossier than before.  Discard cracked pieces.  If they all crack, the rock cannot be heat treated.  If the rock is a little glossy, then heat at 450 degrees for a few hours then let it cool down.  Takes a few flakes off.  If it's glossy and not too brittle, you're good to go.  If it cracks or doesn't get really glossy, then you probably don't want to heat treat at 450 degrees.  You can experiment with higher heat, but I recommend only heating to 350 or 450 and using the rock that responds well at these temperatures.

This only a suggestion.  I'm not an expert in heat treating, by any means.

[bowtarist]

"Dry the rocks in a toaster oven at 250 degrees for a few days."  A few days!!  Dagon, I don't think ,y wife is gonna let me use the t-o for that long.  Some of them are glossy, but seem real hard to chip/flake. 

[mullet]

 I just go to 450dgs and let it go all night and unplug it in the morning. Then wait for it to cool down.

[TRACY]

The piece in the middle on the first pic is Monroe chert and varies in quality but will make sharp points. If you can find the bigger chunks up in the bank , then you'll have better chance of fracture free rock. I find chunks up to a 1/2 brick in size in the creek here at my place, especially after good rains. A couple of years ago at East high school, a couple students in a science class field trip over to clifty creek found some fantastic Thebes points made from this chert.

The piece on the left in the first pic is what you said, "crinoid hash" LOL. I've knapped some points from it, but with all of the fossils it gets to crumble more than flake. The right most rock looks similar to what I occasionally find here and not sure what it's called. I never seem to find any of size or quantity. Hope that helps.

Tracy

[bowtarist]

Thanks Tracy and all others too.  I'll be coming to Cols. possibly sometime this week, I'll give you a heads up before I start moving that way.  Don't know what day yet or if it will even happen.  Hope to talk in person soon.