I DID A PROJECT ON GLASS FRACTURE. I'VE WROTE TO
YOU BEFORE AND I WAS TOLD ABOUT CONCHOIDAL
FRACTURE (THE WAY GLASS FRACTURES). YOU
DESCRIBED IT AS CIRCULAR AND/OR SPIRAL SHAPED.
I, PERSONALLY, HAVE NEVER SEEN GLASS BREAK THIS
WAY. THE RESULTS IN MY TESTS DON'T SHOW THIS
TYPE OF BREAKAGE, EITHER. DO YOU KNOW WHY? CAN
YOU GIVE ME SOME ANSWERS?
I may be there but because glass is usually thin
plates it may not be obvious. I have attached a
picture of obsidian (a volcanic rock that is
basically fused pieces of glass) that shows what
concoidal fractures look like. If you try the
glass again, maybe use a magnifying glass to look
closely, I bet you will see the fracture.