![]() ![]() The latter possibility means that our species is at least 85,000 older than we believe. These spears were made from obsidian by either another species - which had to be extremely crafty and clever - or ancient humans. The remains are so ancient that they actually predate the earliest known fossils of our species by 85,000 years. Remarkably, obsidian tools may even predate humans! Researchers have found what they believe to be the oldest known stone-tipped throwing spears. Ancients may have transported these goods thousands of miles to trade for other goods and services. Historians believe obsidian may have been the very first material actively mined and used to manufacture sharp tools at scale. The colors are thought to be caused mainly by trace elements of inclusions. Rarely, obsidian can be blue, red, orange, or yellow. However, it can also be brown, tan, or green. All sorts of prehistoric artifacts made from obsidian have been found by archeologists, including knives, arrowheads, spear points, and scrapers.īlack is the most common color of obsidian. Over time, ancient peoples learned to break obsidian into tools of various shapes. This means the obsidian breaks into pieces with curved surfaces that are razor thin and extremely sharp. The volcanic glass is thought to be so sharp because of the way it breaks, a pattern geologists call a conchoidal fracture. “It is in this manner: First they get out a knife stone (obsidian core) which is black like jet and 20 cm or slightly less in length, and they make it cylindrical and as thick as the calf of the leg, and they place the stone between the feet, and with a stick apply force to the edges of the stone, and at every push they give a little knife springs off with its edges like those of a razor.” Hester et al. Motolinia, a 16th-century Spanish observer, left this account of prismatic blade production: “The prismatic glass blade is infinitely sharper than a honed steel edge, and these blades can be produced in a wide variety of shapes and sizes,” wrote Bruce A. Don Crabtree who re-discovered the production technique in the 1970s. Metals are hardened to make the crystallites (grains) smaller, but isn't that adding imperfections to the crystal structure? Meanwhile, the obsidian won't deform because the crystallites aren't aligned, so it will keep the sharper edge but it's more brittle and can shatter if dropped.The finest of these prismatic blades were produced in Mesoamerica about 2,500 years ago, according to Dr. So the problem is due to the fact that metal is malleable, which is a result of properties of its crystalline structure. Metal can be shaped as such, but it has to be steeled periodically because it deforms. The conchoidal fractures can create an angle that's ideal for sharpness. My experience in this is based in geology, so I don't know very much about metals, but I think the issue is that it's simpler to use obsidian than steel to get an extremely sharp edge that won't deform. That's why you get conchoidal fractures, right? It's the lack of a crystal structure that allows it to break like that. ![]() Obsidian/glass is an amorphous solid, so it doesn't have any crystal lattice. I think my confusion may be because you go from talking about a perfect crystal lattice to grain size, but I'm not sure. I don't know wether it is technically possible to make a steel edge that thin yet, but the materiel allows for it. Once you try cutting something, the steel edge will bend, and become less sharp. 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. At molecular width, it's edge is hard enough to maintain that razor edge. Obsidian is much, much harder than steel. 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. Steel can be honed to make that cutting edge thinner, and thus, sharper. When you sharpen a knife, you are aligning the serrations to the plane of the edge. Those points will bend to either side of the blade through use,dulling the edge. Steel, on the other hand, is jagged on the edge, forming tiny tooth-like serrations on the cutting edge. Freshly broken pieces of obsidian make perfect, smooth edges that are only a molecule wide at their apex. ![]()
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