Sounds kind of similar to my frustrations with slate. If I just smash a piece of slate I get basically razor blades where each layer separates. But if I painstakingly grind out a uniform edge, it's nowhere near as sharp. Sharp enough to be useful sure; I've prepared a meal with a slate knife and harvested grass and trimmed cord... But I've never come close to the natural shattered-slate sharpness, where I can end up with tiny cuts on my hands from the slivers.

It would be nice to be able to take a vacation back into the neolithic to be able to handle stone tools in their new and pristine condition, and find out how well they are supposed to work.