***Note**: This post talks about [dragon glass][1], 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.*

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From what I understand, dragon glass is [obsidian glass][2]. 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?

  [1]: http://gameofthrones.wikia.com/wiki/Dragonglass
  [2]: https://en.wikipedia.org/wiki/Obsidian