Glass fiber is a material consisting of numerous extremely fine fibers of glass.
Bundle of glass fibers
Glass is a non-crystalline solid that is often transparent, brittle and chemically inert. It has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics.
A glass building facade
A piece of volcanic obsidian glass
Moldavite, a natural glass formed by meteorite impact, from Besednice, Bohemia
Tube fulgurites