Note: This post talks about dragon glass, which may reference various episodes in GoT. The only content that's discussed in this OP is directly related to dragon glass, which inlcudes any conversations/events that may directly involve/mention dragon glass.

From what I understand, dragon glass is obsidian glass. My question is, does GoT ever actually mention why this glass is effective against white walkers? Is it solely because obsidian glass is made at high temperatures by volcanos (with white walkers being "ice-like")? Or, does it have to do with the origin of white walkers, with respect to the Children of the Forest?

A long-forgotten secret is that the Children [of the Forest] actually created the White Walkers as a weapon, by transforming humans into them: this was achieved in a magic ceremony that involved (among other things) plunging a dragonglass shard into a human's chest.

Perhaps, due to the ceremony involving dragon glass, the white walkers now have a negative affinity towards it?

Aside from these two theories, I've got nothing.. can anyone help in explaining this?