IAMZIM
Bronze Member
- Joined
- Apr 23, 2011
- Messages
- 1,567
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- Location
- Butte City, Montana
- Detector(s) used
- ace 250/garret pinpointer, garret AT Gold
- Primary Interest:
- All Treasure Hunting
Why would an obsidian blade be superior over a steel one? Here are some well known facts about obsidian:
1.Freshly broken pieces of obsidian make perfect, smooth edges that are only a molecule wide at their apex. Steel, on the other hand, is jagged on the edge, forming tiny tooth-like serrations on the cutting edge. Those points will bend to either side of the blade through use,dulling the edge. When you sharpen a knife, you are aligning the serrations to the plane of the edge. Steel can be honed to make that cutting edge thinner, and thus, sharper. Steel can theoretically be honed until its edge is just a single molecule wide like obsidian, but here the limitations of the metal come in to play. Obsidian is much, much harder than steel. At molecular width, it's edge is hard enough to maintain that razor edge. At that thickness, the steel blade's serration's (the ones I mentioned earlier) are too weak, and will bend once you try to use that edge. Once you try cutting something, the steel edge will bend, and become less sharp.
2.Obsidian fractures conchoidally down to the very last molecule, so essentially when you break a piece off the very edge is only a molecule thick. It is at least 50 times sharper than surgical steel can get, and I've heard some say as much as 500 times sharper. If you look at obsidian's edge under a microscope, it is a perfectly smooth, sharp line. Steel (sharpened to a razor edge) will look like a toothed saw blade. Obsidian is in fact so sharp that when you are cut with it, it slices between skin cells and leaves no scarring, as opposed to steel which essentially rips apart the cells. The only downside of the spectacular sharpness of obsidian is that it is brittle, like glass, especially when you're talking about the one-molecule thick edge. If it touches anything harder than itself, you need a whole new edge. So, bone and hide are not harder than obsidian is, therefore, it will not dull when cutting them. It would only get dull if it was scraped against something harder than itself, and not need to be "resharpened". And it would not be sharpened in the same way as steel anyway, it would have to be pressure flaked, creating a new "edge" to cut with.
3.Steel is almost always composed of very many separate crystals, rather than one large one.
When steel fractures, it typically fractures along the uneven joins between septate crystals.
Obsidian contains almost no crystals large enough to affect the material's fracture properties and it is for this reason it breaks smoothly and sharply. Because obsidian lacks crystals, it does not break along lines of weakness in the material, it just fractures along the lines of the stress that caused the fracture. This is also why obsidian and similar materials show conchoidal fractures.
When you look at the shape of some fractured obsidian, you are looking at the shape of the shockwave that cracked it. When you look at the shape of some fractured steel, you are looking partly at the shape of the shockwave that fractured it, but mostly at the lines of weakness between the steel's imperfections and the joins between it's crystals.
I have talked to a few hunters that actually use "agate" blades to skin and dress their kills with, and one showed his blade to me and told me he had used it for many years, and never had to resharpen it. However, it is different using a stone blade, because you cannot pry or twist with it, otherwise you greatly risk snapping the blade.
I also find it very interesting reading about the "Hopewell" mound site in Ohio, where archaeologists found ceremonial blades and artifacts made of obsidian, that they claim to have gotten the material from Yellowstone in Montana, probably Obsidian Cliffs. (Where they have also recently found artifacts at the site itself.) Why would these men travel around 1600 miles, just to get this material? To me it's obvious, it is a superior material! True, these blades were determined not to have been used, but only to be ceremonial, but they traveled to get it, because they knew what it was, and how valuable it was to be used as a "cutting" material.
So what do you think? Would an obsidian knife be superior over a steel one? I for one absolutely do!
Obsidian Cliffs, Yellowstone Montana.
Some more reading: Relative frequency of butchering cutmarks produced by ...
Stone Tool, Bison Butchering Experiments in Archaeology/Anthropology Forum Forum
Butchering With Obsidian | Field & Stream
1.Freshly broken pieces of obsidian make perfect, smooth edges that are only a molecule wide at their apex. Steel, on the other hand, is jagged on the edge, forming tiny tooth-like serrations on the cutting edge. Those points will bend to either side of the blade through use,dulling the edge. When you sharpen a knife, you are aligning the serrations to the plane of the edge. Steel can be honed to make that cutting edge thinner, and thus, sharper. Steel can theoretically be honed until its edge is just a single molecule wide like obsidian, but here the limitations of the metal come in to play. Obsidian is much, much harder than steel. At molecular width, it's edge is hard enough to maintain that razor edge. At that thickness, the steel blade's serration's (the ones I mentioned earlier) are too weak, and will bend once you try to use that edge. Once you try cutting something, the steel edge will bend, and become less sharp.
2.Obsidian fractures conchoidally down to the very last molecule, so essentially when you break a piece off the very edge is only a molecule thick. It is at least 50 times sharper than surgical steel can get, and I've heard some say as much as 500 times sharper. If you look at obsidian's edge under a microscope, it is a perfectly smooth, sharp line. Steel (sharpened to a razor edge) will look like a toothed saw blade. Obsidian is in fact so sharp that when you are cut with it, it slices between skin cells and leaves no scarring, as opposed to steel which essentially rips apart the cells. The only downside of the spectacular sharpness of obsidian is that it is brittle, like glass, especially when you're talking about the one-molecule thick edge. If it touches anything harder than itself, you need a whole new edge. So, bone and hide are not harder than obsidian is, therefore, it will not dull when cutting them. It would only get dull if it was scraped against something harder than itself, and not need to be "resharpened". And it would not be sharpened in the same way as steel anyway, it would have to be pressure flaked, creating a new "edge" to cut with.
3.Steel is almost always composed of very many separate crystals, rather than one large one.
When steel fractures, it typically fractures along the uneven joins between septate crystals.
Obsidian contains almost no crystals large enough to affect the material's fracture properties and it is for this reason it breaks smoothly and sharply. Because obsidian lacks crystals, it does not break along lines of weakness in the material, it just fractures along the lines of the stress that caused the fracture. This is also why obsidian and similar materials show conchoidal fractures.
When you look at the shape of some fractured obsidian, you are looking at the shape of the shockwave that cracked it. When you look at the shape of some fractured steel, you are looking partly at the shape of the shockwave that fractured it, but mostly at the lines of weakness between the steel's imperfections and the joins between it's crystals.
I have talked to a few hunters that actually use "agate" blades to skin and dress their kills with, and one showed his blade to me and told me he had used it for many years, and never had to resharpen it. However, it is different using a stone blade, because you cannot pry or twist with it, otherwise you greatly risk snapping the blade.
I also find it very interesting reading about the "Hopewell" mound site in Ohio, where archaeologists found ceremonial blades and artifacts made of obsidian, that they claim to have gotten the material from Yellowstone in Montana, probably Obsidian Cliffs. (Where they have also recently found artifacts at the site itself.) Why would these men travel around 1600 miles, just to get this material? To me it's obvious, it is a superior material! True, these blades were determined not to have been used, but only to be ceremonial, but they traveled to get it, because they knew what it was, and how valuable it was to be used as a "cutting" material.
So what do you think? Would an obsidian knife be superior over a steel one? I for one absolutely do!
Obsidian Cliffs, Yellowstone Montana.Some more reading: Relative frequency of butchering cutmarks produced by ...
Stone Tool, Bison Butchering Experiments in Archaeology/Anthropology Forum Forum
Butchering With Obsidian | Field & Stream
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I didnt even get to join a band wagon or anything. 
