JiK wrote "For incredibly sharp tools, I'm told that freshly knapped flint is superior to any modern steel. One surgeon who actually tested using "flint scalpels" (made for him by a friend who was a "re-enactor") was so impressed he attempted to learn how to make them, but conceded he'd never be able to learn the stone age skill needed to make them consitently."

When I was studying archaeology 20-odd years ago I saw a film clip of an American Indian knapping flint to make various stone implements; the clip might have already been about 15 years old. Whether he was a "Re-enactor" depends on your definitions I suppose but he was quite elderly at the time and very good. Certainly he was reported to have later required open-heart surgery and made a set of blades for the surgeon to use during the surgery, after sterilisation (of the blades, silly). The surgeon was reported to have been quite impressed.

The eye surgery I mentioned was a later event using obsidian (volcanic glass) blades made by an archaeologist who was researching stone-tool technology. I'm not sure of the exact details (it was a long time ago) and I suspect the surgery may not have been on a person, as it seems to have been done to check whether the obsidian edge performed as well as, or better than, the usual steel scalpels.

Flint is silicified with extremely fine grain and obsidian is glass (silica) with no grain but they're extremely sharp. When teaching in the northern suburbs of Melbourne (where the 'uniform' of the time included hair spikes with orange and blue hair gel) I got a friend of mine to do a demonstration of flint knapping the way Australian Aboriginal people had done it. The students were warned of the sharpness but were disbelieving until they experimented. Bandaids were always on hand.

Fired fine-grained ceramics are similar to flint. When the Overland Telegraph (Darwin - Adelaide) was connected through Alice Springs in 1872, the linesmen had much trouble with Aboriginals along its whole length pinching the insulators to use to make blades and other implements. The problem disappeared when small piles of broken insulators were left at the bases of the poles along the line for them to use.

Cheers, Rowan