Paleo knife?

katana · 28th June 2011, 04:03 PM

Hi
Chert is a form of sedimentary rock. Notice the whitish flecks (inclusions). Chert varies both in colour and hardness.

" .....Chert is a microcrystalline or cryptocrystalline sedimentary rock material composed of silicon dioxide (SiO2). It occurs as nodules, concretionary masses and as layered deposits. Chert breaks with a conchoidal fracture, often producing very sharp edges. Early people took advantage of how chert breaks and used it to fashion cutting tools and weapons......"

Cryptocrystalline is a rock texture made up of such minute crystals that its crystalline nature is only vaguely revealed even microscopically in thin section by transmitted polarized light. Among the sedimentary rocks, chert and flint are cryptocrystalline.

A microcrystalline material is a crystallized substance or rock that contains small crystals visible only through microscopic examination

Judging, again, by the pictures there seems to be inclusions which are not crypto/micro crystalline. Perhaps some clear close-ups might help of the rock surface and percusion / pressure flaking areas.

Kind Regards David

VANDOO · 29th June 2011, 01:06 AM

THE MATERIAL SHOWN LOOKS LIKE A POOR CHOICE FOR STONE TOOL OR BLADE BUT SOMETIMES THEY NO DOUBT USED WHAT WAS AVAILABLE. THE MATERIAL REMINDS ME OF THE BRICK IT IS LAYING ON.
I HAVE SEEN TOOLS MADE OF BRICK, BROKEN POTTERY, GLASS,QUARTZ, SLATE, LIMESTONE AND VARIOUS IGNEOUS ROCKS. SLATE AND OTHER SEDIMENTARY ROCKS ARE USUALLY SHAPED BY GRINDING OR PECKING AS THEY DON'T FLAKE WELL.
PERHAPS SOME OF THE SOFTER ROCKS WERE USED FOR TEACHING TECKNIQUES TO BEGINNERS. NO DOUBT AN EXPERT FLINT KNAPPER PREFERRED GOOD MATERIAL BUT NOT EVERYONE WAS BLESSED WITH A GOOD SUPPLY OF OBSIDIAN OR FLINT SO THERE IS A WIDE VARIETY OF ODD ARTEFACTS OUT THERE. GOOD FLINT OR CHERT OR OBSIDIAN WAS WIDELY TRADED IN NORTH AND SOUTH AMERICA.

LOOK AROUND FOR A POINT SHOW (ARTEFACT SHOW) IN YOIUR AREA AND SOMEONE THERE SHOULD BE ABLE TO GIVE YOU SOME GOOD INFO ON IT. GOOD LUCK

David · 29th June 2011, 02:39 AM

Quote:

Originally Posted by katana

Chert is a form of sedimentary rock. Notice the whitish flecks (inclusions). Chert varies both in colour and hardness.

Well so much for my high school geology education...

Rust Collector · 4th July 2011, 02:07 AM

Sorry it took so long to get back with better pictures... I've been having trouble getting as close up as I wanted but I think I've go some that illustrate my points. If nothing else this thread has given me an appreciation for the great photography that I see all the time on this forum and the idea that I need a better camera.
I am more convinced the material is chert, it is riddled with crystal occlusions, fractures concoidally and seems to meet the rest of the charataristic associated with it.

fearn · 5th July 2011, 05:01 PM

I'm having trouble seeing the conchoidal fractures. Atlantia's post in #7 shows them quite clearly. Conchoidal fractures are what one sees when glass breaks. Is there a way you can indicate where you are seeing conchoidal fractures?

As for cryptocrystalline (crystal structure too small to see), I see crystals, and I see lots of evidence (the holes along the edge, for one) where there are fairly large crystals.

F

Tim Simmons · 5th July 2011, 05:29 PM

I am having difficulty seeing anything on this stone that has been cause by humans. Even some of the Australian Aboriginal basic stone tools, noted for there lack of sophisticated napping and grinding show clear signs of the human hand. I do realise that this sort of thing is so difficult to present through a PC.

Atlantia · 5th July 2011, 09:16 PM

Sorry Rust, I've got to say that I'm still of the opinion that this is a natural shape.
I also don't think it is the kind of chert that is used for tools.

aiontay · 6th July 2011, 03:58 AM

In my completely unexpert opinion, it is a natural, not man made stone artifact.

However, I have on one occasion made a discodial knife (breaking a flake of a rounded rock which makes a disc shaped flake) from a piece of sandstone, and it did result in a very sharp edge that would cut. The edge quickly broke up and you couldn't really re-flake it to sharpen it. Pretty lousy material for a blade, but if you had nothing else you could skin a rabbit or cut down a small sapling in a pinch, but it would be useless after that one task.

4th July 2011, 02:07 AM	#4
Rust Collector Member Join Date: Sep 2010 Posts: 11	Sorry it took so long to get back with better pictures... I've been having trouble getting as close up as I wanted but I think I've go some that illustrate my points. If nothing else this thread has given me an appreciation for the great photography that I see all the time on this forum and the idea that I need a better camera. I am more convinced the material is chert, it is riddled with crystal occlusions, fractures concoidally and seems to meet the rest of the charataristic associated with it. Attached Images

28th June 2011, 04:03 PM	#1
katana Member Join Date: Jan 2006 Location: Kent Posts: 2,658	Hi Chert is a form of sedimentary rock. Notice the whitish flecks (inclusions). Chert varies both in colour and hardness. " .....Chert is a microcrystalline or cryptocrystalline sedimentary rock material composed of silicon dioxide (SiO2). It occurs as nodules, concretionary masses and as layered deposits. Chert breaks with a conchoidal fracture, often producing very sharp edges. Early people took advantage of how chert breaks and used it to fashion cutting tools and weapons......" Cryptocrystalline is a rock texture made up of such minute crystals that its crystalline nature is only vaguely revealed even microscopically in thin section by transmitted polarized light. Among the sedimentary rocks, chert and flint are cryptocrystalline. A microcrystalline material is a crystallized substance or rock that contains small crystals visible only through microscopic examination Judging, again, by the pictures there seems to be inclusions which are not crypto/micro crystalline. Perhaps some clear close-ups might help of the rock surface and percusion / pressure flaking areas. Kind Regards David

29th June 2011, 01:06 AM	#2
VANDOO (deceased) Join Date: Dec 2004 Location: OKLAHOMA, USA Posts: 3,138	THE MATERIAL SHOWN LOOKS LIKE A POOR CHOICE FOR STONE TOOL OR BLADE BUT SOMETIMES THEY NO DOUBT USED WHAT WAS AVAILABLE. THE MATERIAL REMINDS ME OF THE BRICK IT IS LAYING ON. I HAVE SEEN TOOLS MADE OF BRICK, BROKEN POTTERY, GLASS,QUARTZ, SLATE, LIMESTONE AND VARIOUS IGNEOUS ROCKS. SLATE AND OTHER SEDIMENTARY ROCKS ARE USUALLY SHAPED BY GRINDING OR PECKING AS THEY DON'T FLAKE WELL. PERHAPS SOME OF THE SOFTER ROCKS WERE USED FOR TEACHING TECKNIQUES TO BEGINNERS. NO DOUBT AN EXPERT FLINT KNAPPER PREFERRED GOOD MATERIAL BUT NOT EVERYONE WAS BLESSED WITH A GOOD SUPPLY OF OBSIDIAN OR FLINT SO THERE IS A WIDE VARIETY OF ODD ARTEFACTS OUT THERE. GOOD FLINT OR CHERT OR OBSIDIAN WAS WIDELY TRADED IN NORTH AND SOUTH AMERICA. LOOK AROUND FOR A POINT SHOW (ARTEFACT SHOW) IN YOIUR AREA AND SOMEONE THERE SHOULD BE ABLE TO GIVE YOU SOME GOOD INFO ON IT. GOOD LUCK

5th July 2011, 05:01 PM	#5
fearn Member Join Date: Dec 2004 Posts: 1,247	I'm having trouble seeing the conchoidal fractures. Atlantia's post in #7 shows them quite clearly. Conchoidal fractures are what one sees when glass breaks. Is there a way you can indicate where you are seeing conchoidal fractures? As for cryptocrystalline (crystal structure too small to see), I see crystals, and I see lots of evidence (the holes along the edge, for one) where there are fairly large crystals. F

5th July 2011, 05:29 PM	#6
Tim Simmons Member Join Date: Dec 2004 Location: What is still UK Posts: 5,854	I am having difficulty seeing anything on this stone that has been cause by humans. Even some of the Australian Aboriginal basic stone tools, noted for there lack of sophisticated napping and grinding show clear signs of the human hand. I do realise that this sort of thing is so difficult to present through a PC.

5th July 2011, 09:16 PM	#7
Atlantia Member Join Date: Jun 2008 Location: The Sharp end Posts: 2,928	Sorry Rust, I've got to say that I'm still of the opinion that this is a natural shape. I also don't think it is the kind of chert that is used for tools.

6th July 2011, 03:58 AM	#8
aiontay Member Join Date: Nov 2008 Posts: 88	In my completely unexpert opinion, it is a natural, not man made stone artifact. However, I have on one occasion made a discodial knife (breaking a flake of a rounded rock which makes a disc shaped flake) from a piece of sandstone, and it did result in a very sharp edge that would cut. The edge quickly broke up and you couldn't really re-flake it to sharpen it. Pretty lousy material for a blade, but if you had nothing else you could skin a rabbit or cut down a small sapling in a pinch, but it would be useless after that one task.