Obsidian

[Greg Corning <cogre@xxxxxxxx>]

Arthur:

	I was not aware that one could "carve" obsidian or any other glass-like
stone. One "knaps" obsidian and some other types of stone. You hit it
with a hammer stone, usually right on an edge, and it flakes off chips to
leave the desired shape.

	I've been told that obsidian has zero "grain" or crystal structure to
it. [I have forgotten the technical/scientific term for this; is it
amorphous structure?] You probably know that it is great for making
blades such as arrowheads, choppers, knives, and so on. I've found all
kinds of people who have revived, as it were, the art of working
obsidian, flint, and other such stones to replicate prehistoric tools. In
many parts of the US (and elsewhere, I am sure) classes are offered in
these skills. It is truly impressive to watch someone take a hunk of
stone and make a symmetrically perfect Mousterian or Folsom point.

	I should add that flint, chert, and some other kinds of stone that are
worked into blades are not truly acrystalline as is obsidian; flint, for
example, has crystal structure to it but it is a structure amenable to
knapping. Chert has to be heat-treated before it can be worked, I am
told.

	Look up the Society for Primitive Technology. Oddly, they have (or used
to have) a web site.