You still need heat, but you can make fiber from basalt: https://en.wikipedia.org/wiki/Basalt_fiber https://en.wikipedia.org/wiki/Basalt_fiber Among other thi

You still need heat, but you can make fiber from basalt: https://en.wikipedia.org/wiki/Basalt_fiber https://en.wikipedia.org/wiki/Basalt_fiber Among other things its used to make a type of rebar.