Olive Green Chert perhaps?

[buckeye]

I found this while snooping around a nearby creek where they weredigging an area out for a bridge. I think this came out of the bedrock. I wanted to try and find more but I got rained out. Whatever it is, I also have a chipped arrowhead that looks to be made out of the same material. I tried flaking it and it does cleave well. Anyone have any ideas?


Thanks,
Bryce

[arappaho]

Hey Buckeye,
I know the material, but have never been sure of what exactly to call it.
It is like a combination of quartz and chalcedony, which isn't much of a
stretch since chemically chalcedony is quartz. And some of it has a sugary
texture like a fine grained quartzite. And chert is a chalcedony. Flint is a
chalcedony. Jasper is a chalcedony. There is a fine line, sometimes, between
them. Sometimes you have to see the rock insitu to be able to identify it.
I know it has been used prehistorically as a knapping material.
For the stuff you have there I'm leaning toward a 'hot' rock like quartz.
I don't know tho. Hope this helps somehow......?

Joe

[buckeye]

Thanks Joe,
I am gonna go back to the spot this weekend to see if I can find a good seam of it. I will let ya know if I find a good deposit of it. It does seem to flake well.
Thanks,
Bryce

[4cornersrocks]

I go jasper hunting all the time and that is definetly jasper/chert. You might get lucky and find petrified wood, artifacts or fossils made out of the same material. I have some pet. wood that looks just like that, just with bark and ring patterns. The chipping (conchoidal fracture) is a good way to determine if a rock will take a polish also. Nice find!
Dude

[arappaho]

Yeah, you're right, 4corners. It looks like jasper/chert and there is petrified wood to be found in the area, too. It's just that our local Piedmont rocks have been so banged up and moved and morphed around here that I am hesitant to label them any one thing. They could be alittle of this, and then, alittle of that. But jasper/chert seems safe enough.
Joe

[scott]

This may help a little in distinguishing between chert, chalcedony, and flint.

While the article doesn't mention Jasper it's still very helpful.

www.theaaca.com/Learning_Center/flintvs.htm

[lauriesrocks]

I would like to put my two cents worth in on this nomenclature. I have some disagreements with the article referenced above. It states, "mineralogically speaking, flint is black chert". Not so! First, "flint" is not even a mineralogical term! The definition of the term "flint" depends on the geographical location of the definer. The term originally came from Norway, referring to "flinders", or sharp fragments. The most famous flint is that from the White Cliffs of Dover, in England, where the superbly pure material was excellent for making sparks, and thus became the standard for use in "flintlock" rifles. This material was commonly used for ballast in the bowls of ships sailing to the New World when America was first being settled, and was adopted by our soldiers for use in our rifles used in the Revolutionary War, as the "sparking" quality was far superior to what was then available. This is where the term flint was first used by Americans. Over the decades, the term has come to denote any form of cryptocrystalline quartz that has conchoidal fracture (ie, breaks like glass with sharp edges and saucer shaped fractures). If you live in Texas, you have local types of agate, such as "Alibates Flint", that is called flint. In the far west, obsidian is often called flint. In some parts of the midwest, jasper is called flint. In Montgomery County, North carolina, you have two kinds of flint, regular flint, which is actually rhyolite, and "white flint", which is actually milky quartz. In Tennessee, chert is called flint. I can cite numerous other examples, but you get the point. There is no distinct mineralogical definition of the term flint. All of these materials have been used by aboriginals for implement manufacture. If we are going to get more technical, then we would not be speaking of mineralogical definitions, but petrological definitions, ie rocks, not minerals. Chert is a form of cryptocrystalline quartz that is formed in sedimentary rocks, hence the black chert nodules commonly found in Limestone. You will not find chert in Piedmont North Carolina. It may look like chert, may have the same characteristics as chert, but would not have been formed in the same way. As for the material in question, since it was found in or around Orange County, NC, it could not be chert. There are dozens of forms of cryptocrystalline quartz, such as jasper, agate, chert, chalcedony, etc. Agate itself has literally a thousand varietal names, just look at any Lapidary Journal! All I can say for sure is that the material you have appears to be a form of cryptocrystalline quartz. The generic term "flint" is about as accurate as any, without a detailed petrologic analysis. It is definitely not chert. Chalcedony would not apply very well either. This term should only apply to a more precious variety of cryptocrystalline quartz, usually with a "waxy" luster, and often of botryoidal (ie bubbly) form, such as onyx, sardonyx, chrysoprase, some agates and jaspers, carnelian, etc. Jasper simply refers to the opaque variety of cryptocrystalline quartz that is of an yellow, brown or orange color. Agate is the form of chalcedony that is usually somewhat translucent with banded colors. The material you have could be termed jasperoid, which would be an impure form of jasper, with poor conchoidal fracture. Now that I've got you totally confused, I'll quit while I'm behind!

[arappaho]

Well Done! Well Done! And Thank you for tackeling that difficult
issue of terminology, Laurie. Generic terms such as flint, soapstone, etc. cause alot of confusion and tend to gloss over the true answers. And as you can see, the link Scott provided was prepared by archaeologist, not geologist, so across sciences
you have misuse and mis-representation. The confusion is understandable.
You have helped to clear up a real problem I have been having with what to call this particular type of material by pointing out the fact that true chert is formed in sedimentary rocks and so would not be found in our Piedmont. So the material that I,( and
others), have been finding in the Piedmont and have been calling chert, would actually be jaspers. The colors fit, I'll have to check hardness. One question I have is what are the probabilities of any chert forming along the Coastal Plain - Piedmont boundary?

But your explanation lays it out pretty clearly and is a good synopsis to refer to when in question. And I got plenty of them! ;D

And let me throw in this tidbit of info while we are kindof on the subject. As you said, the flint from England is black or dark grey.
Well 'flint' from France and parts of Spain is an orangish-brown color, sometimes refered to as 'Rootbeer' colored. Archaeologist
investigating early historic settlements can sometimes tell where the occupants were from, ie. English, French, or Spanish, by the color of their gunflints.

Thanks, Joe

[buckeye]

Hey,
Thanks you guys!
That was a good explanation Laurie. I think I have a good answer as to what it is now... and a way to figure out what I an collecting in the future.
Thanks,
Bryce C

[lauriesrocks]

Arappaho, it would be theoretically possible for chert to have formed in some of the Eocene and Miocene sedimentary marls and limestones in the coastal plain, however I am not aware of any instance of this. These rocks are relatively new, geologically speaking, and have not been buried deep enough and long enough to have gone through the intense heat and pressure needed to bring about the paragenesis of chert. I would not automatically call the material used in the Piedmont for the manufacture of stone implements to be jasper. The vast majority of it is rhyolite, a volcanic rock. If you ever get a chance to go to Morrow Mtn. State Park in Stanly County, you will see an entire mountaintop of rhyolite that was quarried by the ancients to make tools with. When this material is freshly quarried, it is normally a slate blue-black in color, some lighter, some darker, and sometimes with bands of lighter material. After centuries of weathering, which is typical of most field collected arrowheads, the material forms a "patina" or crust of lighter color, usually a beige or whitish tint. Sometimes a freshly broken arrowhead will reveal a dark central core surrounded by a lighter outer crust. Rhyolite outcrops throughout the Piedmont "slate belt", but the best material comes from Montgomery, Stanly, Davidson, and Randolph counties. Only very brown, yellow, or red material should be called jasper. There have been some superb jasper artifacts found in and around Yadkin County, NC, such as those from the well known Donnaha site, some of it is very beautiful in color, and ranges from brown to red to yellow. Even some green has been found here. Some researchers at Wake Forest University once determined that this material was quarried somewhere in Surry County, but I could never pin down a location. There is a location in Stokes County where a beautiful translucent banded agate, some of it "crazy lace", was quarried by natives to make implements. These ancients were excellent field geologists! As for the White Cliffs material, I did not say it was black. It is in fact of the same identical form and color of the French material. Very translucent and of a light root beer color, sometimes with yellowish bands, and a white outer "rind". It is very beautiful material.

[arappaho]

Not to belittle the issue, but I guess the main cause for my hesitation in labeling many of these type rocks found in the Piedmont is that darn Triassic Basin where we know some types of chert in limestone occur. In southern Durham Co there is a brown with reds and yellows chert in limestone with petrified wood with the same coloration scattered about. I have found water-worn cobbles of every grade of chalcedony from very fine crypto-crystalline to a sugary-texture more resembling a quartzite. But, I gotta admit, I like the term "jasperoid" for the stuff Buckeye is finding. It would be nice to see it in the ground.

My main reason for asking about the Coastal Plain- Piedmont margin is because of deposits of a material in the Moncure, NC area that has always been called chert. There is a thin band of a
type of the Chatham Triassic Basin running from just south of
Hwy 64 to just south of the Deep River. I have collected from a couple of areas in this basin on either side of the Haw River less than a mile apart. Not that you will be able to tell much from this photo I'm using it anyway.



The three cabs at the top of the pic were dug from a vein very low down by the river. The vein was a very consistent dark brown
and this material is translucent. The other cabs are made from material gathered from the surface on the ridge above the river.
They are multi-colored and opaque and fit the definition for jasper perfectly. But, if you can't see the label in the pic, I just call
it all chalcedony.

And Rhyolite. In this area Rhyolite is as generically used as Flint is in other areas glossing over the true unique identities of the many metavolcanic, metasedimentary, metamudstone, siltstone,
and argillites, dacites and andesites that compose the slate belt.
Here's another bad photo.



I found this stumbling thru a developement recently. I saw the midsection first, picked it up and started to walk away when I noticed the two fresh breaks on either end. I said 'What the Heck' and went back to where I picked it up and started scratching in the dirt. Sure enough, up popped the bottom portion. I have spent several hours and been back several times looking for that point but I'm afraid it is a lost cause.
But this piece is a perfect example of what is often lumped under the label Rhyolite. The "bands" you see running thru the piece are often mis-identified as 'flowbanding' but are actually due to some sort of sedimentary process. I basically believe that alot of the mysteries of the Carolina Slate belt have yet to be discovered and I like to psyche myself up to the possibility that anything at all could've happened around hea'. ;D

And, Laurie, you are correct as usual. You did not say that the
English flint was black. It was stated in the article referenced above that," Dover flint is actually a black chert." or something like that. My apologies. But don't shoot the messenger, it's those crazy archaeologists that have been and do distinguish English Dover flint from French Honey-colored flint on the basis of color.
For much better pictures of this than I can provide go to;
www.ksartifacts.info/ksartifacts1.htm.
Scroll down into the glossary to the word flint and click on CS21 and CS22 respectively.

Joe

[arappaho]

Sorry folks. I don't seem to know how to make a link work.
But if you are interested you ought to be able to find the page with the
info there. ks stands for Kansas.
Joe

[buckeye]

Hey you guys, I thought I should probably clarify something. The material I found was actually in Alamance county on the outskirts of Mebane. I know it's a small detail but I thought maybe the location would mean something?

Anyways, I think I have also found quite a bit of that Rhyolite in the area. The outside of the nodules will be white but when I klink them against metal it sounds alot like a flint/chert/workable material will sound. After I heard you talk about that Joe I went outside and tried flaking a piece of it that I brought up to the house and sure enough the inside of it is a dark grey color.
neat stuff,

BTW, made the top picture smaller so it's easier to read the post!

Bryce C