Topics include oceanic, volcanic and chemical jaspers, 'thunder eggs', chalcedony, banded agate, lace agate and natural glasses
. The entire lecture series comprises 25 videos.
Moreover, industrial spherules may contaminate the natural glasses, both at the outcrop and during laboratory treatments [3-5].
Admittedly, lechatelierite inclusions have been taken as a criterion to distinguish natural glasses related to impacts from most common industrial glasses.
Then comes a sequence of 20 generous chapters on major minerals and other materials of ornamental interest--including two chapters on diamond and one each on, e.g., corundum, beryl, chrysoberyl, tourmaline, garnets, quartz, opal, jade, "The Natural Glasses
" and marble.
Fifty-eight minerals, natural glasses, and synthetic samples have been characterized in the past 25 years.
Although the laboratory staff focused primarily on meteorite research, they also analyzed minerals, mineral separates, and natural glasses, several of which became electron-microprobe standards.