>>> "J.A. Drew Diaz" <[log in to unmask]> 4/01/00 5:01:47 >>> wrote: 

"A few years ago Fine Wood Working Magazine had an article
wherein someone was making coffee tables  w/ 2 layers of glass
the lower piece was cracked through a whole in the wood frame w/ a
spring punch."

Drew

I suspect in this case that the glass was tempered (often referred to as safety glass, of which it is only one kind).  When broken, it breaks into many small pieces, or dice, just like car windscreens in the 1970s and early 1980s did (before they started using laminated glass).

It can be broken by hitting it with a hammer and punch - indeed that is a routine quality test (bit destructive though!).

The 'glacier glass' is unlikely to have been tempered glass, because it is my understanding that the technology for this type of glass is mid-late 20thC.

david