glasses  search
BTigneous rocks
 .volcanic rocks
 ..glasses
NTobsidian
 palagonite
 perlite
 pitchstone
 volcanic glass
 zirkelite
UFglass
RTpyroclastics
 amorphous materials
 tektites
 Darwin glass
 devitrification
 vitrification
 maskelynite
 palagonitization
SNUse volcanic glass if applicable. Glass materials may be used for natural, nonvolcanic materials. Before 1981, search pyroclastics and glasses.