Some people going through cornea surgery are shocked that their surgeon is doing this delicate eye surgery with a sharp rock. Obsidian microblades have the advantage of yielding a cleaner cut from their spalls than is available from any sharpened metallic blade.
As I write about knives in the magazine Knife World and the Krause Publications knife annuals I have a natural interest in knives of all sorts, including those made of stone. On one trip
I picked up some blades from Mississippi knife maker Ken Austin and used them on later hunts for hogs in Texas and buffalo in South Dakota.
No doubt about it. These knapped flint and obsidian blades can cut very well. Their shortcomings are that they are brittle and cannot be subjected to any twisting motion or lateral pressure. They also tend to gum-up with fat and hair worse that steel blades. Stone projectile points will also not hold as keen a point as a steel-pointed arrow. This is why the American Indians replaced their stone blades and arrow points with steel ones as soon as they could.
As unique utilitarian items that are both historical and objects of beauty, I have a soft spot in my heart for stone knives and the men who still produce them. My most recent article on these blades is in the Knives 2010 which is just appearing on the shelves.
It is an interesting modern analogy that ceramic blades are now being introduced which are hard, super sharp, give no metallic taste to the materials they work; but are as brittle as the original stone blades. If you do not have a ceramic blade in your kitchen, try one. I think that you will like it so long as you use it just for slicing. Ceramic blades, like the flint ones, are not appropriate for jabbing, prying, twisting or punching through metal can lids.