Dragonglass

Dragon Glass is a substance found by the First Men. It is hown ins Season 2, which is found by Jon Snow of the Night's Watch.

Before Season 2
This object is carved in by the First Men and are shaped in arrowheads.

Season 2
Obsidian or Dragon Glass was the only substance other than fire to be a known effective weapon in use against White Walkers. Jon Snow found a stash of arrowheads and other sharp pieces which he distributed for use among the Night's Watchmen.

Appearance
The arrowhead is wired and hangs from a silvertone metal handmade bracelet with lobster clasp. I make all my bracelets adjustable up to 8" long because I beleive that good jewelry shouldn't just fit "some people."

Arrowheads are hand carved and may vary slightly in shape but not in color.