There are many excellent guides to rocks and minerals, both in print and online.[1] But there's no real substitute for handling actual rocks and minerals to get a feel for what can be done with them. For cutting tools, quartz is less than ideal, since quarts crystals are generally smaller than the tools we would like to make. Large slabs of quartzite are plentiful, but embedded minerals can cause them to fracture in inopportune places. The chalcedonies, being non-crystalline, are perfect for making stone tools, but the black gold of the stone-tool maker is obsidian. If you can find it, you'll have the easiest time learning how to knap, the term used for making stone tools. Once you are proficient at knapping obsidian, you can try the other silicates. If you can't find obsidian, try using glass; It looks and feels like obsidian and is much easier to find.

Figure 2-3. Tools for Knapping Stone

Colored glass, brown or green, is the best glass for beginners, since you can see where the flakes have come off. Look for a bottle with a thick, smooth, flat bottom.[2] Bottles with raised designs on the bottom are not as good as those without, since these patterns are hard to get off. Once you have a bottle, you'll need some tools. First, you really need a pair of glasses to cover your eyes; as much fun as this is, it's not worth losing an eye. Prescription glasses or sunglasses are fine, but safety glasses with side shields are the best. Second, you need a pair of work gloves to protect your hands from cuts, and you ought to have some band-aids on hand, in case you get careless. Next, provide yourself with a leather pad, six inches square, for holding the tool in your hands or against your leg. You will need a tool for spalling, making your initial flake, and for this you can use a big common nail, six inches long or longer. For a pressure flaker you can use an antler tine or a three inch length of 3/16 inch welding rod mounted into a wooden handle. Finally, you can use a screwdriver for making notches in your finished stone tool. Once you have your tools, you are ready for spalling.

If you were making a tool from a rock, you'd have knock, or spall, a nice big flake, or tool blank, off of your original piece of stone. If you're spalling from a bottle, your tool blank will come from the bottom of the bottle. You take the empty bottle, drop your spalling nail, point down, into the bottle, place your thumb over the mouth of the bottle and shake it like a can of spray paint. Half the time, you can get the bottom of the bottle to pop out, forming a nice, round tool blank. There may be some jagged points hanging off the edge. To get rid of these, hold the tool blank in your gloved hand and whack any jagged points off, using your spalling nail like a little hammer. When you are finished, you should have a flat glass disk as a tool blank.

Figure 2-4. Pressure Flaking

Most of your work will consist of pressure flaking. Wrap your tool blank in your leather pad and hold it in your gloved hand, as shown in Figure 2-4, with your fingers on top. You can rest your gloved hand on your leg for extra support. Hold your pressure flaker in your other hand, put the tip on the edge of the tool blank, and press. You don't hit it or pry it, just press straight into the glass with the pressure flaker, as if you were trying to shove it right into the glass. A flake will pop right off and you ought to take a moment to look at the shape of that flake.

The silicates break with what's known as a conchoidal fracture. If you look at a bullet hole in a piece of glass, you'll see that the entrance side is just big enough for the bullet to go through, but the exit side is much bigger. In profile, the flake scar, the place where the flake used to be, is cone-shaped. If the bullet had struck the glass along the edge, only half the cone would be there because the other half of the cone would be lost in the air. That's what your flake scars should look like, since you'll always be taking flakes from the edge of the tool. Now, if you fit that flake back onto your tool blank, you can see how it came off. The fat, bulbous end is where your pressure flaker was and it tapers out to a thin, razor-sharp edge. You might think that this razor-sharp edge is where the action is, but it is so thin that it is easily broken. No, the edge of your tool will be made up of the flake scars, the places where the flakes used to be. The little point where the bulb of the flake came off is both sharp and strong, so the edge of your tool will not be easily broken.

Now, those flakes might be long or short, depending on how you hold your tool. If you hold it at an angle to the tool blank, a little short flake will pop off. This is the kind of flake you'll be making at first. But as your tool takes shape, you'll want to take off longer flakes to cover the surface with pretty flake scars. To do this, you push the pressure flaker straight into the edge of the tool blank and press with all your might. Then, when you're pressing as hard as you can, just give a little downward flick, as shown in Figure 2-5, and a long flake will pop off. This is the kind of flake you should be making by the time you finish your tool.

Figure 2-5. Long and Short Flakes

Figure 2-6. Making the Edge of the Tool

Before you can take off the long flakes, you'll need to set up the edge of the tool. After taking your first short flake off, say, side A, turn the tool blank over in your hand and take the second flake off side B, right next door to your first flake. Turn it over again and take another flake off side A. These will be short flakes, just to set up the edge of your tool blank. Remember, you're always pushing flakes down, into your palm, not up, into your eyes. Whatever side you're taking a flake from, that side should be against your palm. Keep going around the tool blank, taking a flake from one side and then turning your tool blank over and then taking a flake from the other, until you get back to where you started. The edge will now be serpentine, like a snake, with one point on side A, the next on side B, and so on, as shown in Figure 2-6. This edge is sharp and serrated, like a steak knife, so don't cut yourself.

Now, the bottom of the bottle was probably concave on the outside and convex on the inside. Stone tools are usually bi-facial; both sides are worked until the tool is lens-shaped in cross section. Whether you are using a stone or a bottle, the two sides of your tool blank are probably not symmetrical. To get your tool into a lens-shape, you need to take long flakes off the concave side and short flakes off the convex side. Now, it would be a lot easier to take long flakes off the convex side and short flakes off the concave side, but that would make the convex side even more convex. Your goal on this second round of flakes is to get as close to a lens shape as you can, as in Figure 2-7.

Figure 2-7. Getting a Lens-Shape

Now, this is probably the hardest part to learn. Imagine a line down the center of the edge of your tool, the center line. You'll notice that you can only take flakes from below this center line. The best thing to do is to look for a point from a previous flake scar which is below the center line and use this point as a platform, a place to put your pressure flaker, for taking off another flake. Each flake you take off makes a platform for a flake on the other side of the tool. For example, if you take a flake off of side A, it makes a point on side B. You can use this point as a platform to take a flake off of side B, and that makes another point on side A. But if you have a point on side B and you try to use it as a platform for a flake off of side A, you're trying to remove so much glass at once that you'll have a hard time getting the flake to come off at all. So it becomes like a chess game, where you're thinking a couple of moves ahead. You want to take a nice long flake off of Side A, but there's no good platform there. Just take a little short flake from the same place, but on Side B, and that will set up a nice platform on Side A. It's really not so hard, once you get the hang of it.

Figure 2-8. Platforms are Always Below the Center Line

Figure 2-9. From Beer Bottle to Arrow Head

If you just keep going around in circles, your tool will wind up being a circle. So at this point you want to start looking for where the tip is going to be and where the base is going to be. That way, you can take more flakes off here and fewer flakes off there to get your tool into the shape that you want it to have. By now, you should be taking long flakes off of both sides, the longer the better. Those flake scars will travel all the way across the face of the tool, until none of the original surface, the cortex, is left. If you want to make some notches, you can use your notching tool, the one shaped like a screwdriver. You use it the same as your pressure flaker, except that instead of taking a flake next door to the one before it, you take it off of the same place: a flake from side A, and then a flake from side B in the same place. The shape of the notcher lets you make long, narrow notches, as opposed to the semi-circular flakes removed by the pressure flaker.

That sounds pretty good to me. If you were stuck on a desert island or something, you wouldn't have to starve. You could make your own arrowheads, spear points, knives, or what-have-you. You might not have glasses, gloves, and band-aids, so if that ever happens, you should be real careful. And if you're ever walking along through the grass and you hear a little ticking noise, like little stones hitting together, you might just spend a little time thinking about old Unktomi, so I don't go extinct.

ImportantQuality Assurance

How do you know your arrowhead is good enough? It should have a bi-facial, serrated edge and its surface should be completely covered with flake scars. If you were a Paleolithic teenager, you shouldn't be embarrassed to show it to your father. Write up your procedure in your notebook, as described in Appendix B, and include a photograph of your arrowhead.



See, for example, Reference [85].


This project was inspired by Reference [87].