I was under the impression -- perhaps false -- that "Pyrex" and other borosilicate glasses didn't fracture as easily as natural untempered glasses, but a light impact resulting in a very sharp concoidal sliver from the inside rim of one "ovenware" top that we have made me think again. Isn't most "ovenware" tempered? I know tempering is an entirely separate consideration from composition, but are untempered borosilicates any more or less apt to fracture or shatter than regular glass?
TIA Mark 'Sporky' Stapleton Watermark Design, LLC