- "The Maesters call it 'obsidian'."
- ―Samwell Tarly
Dragonglass is a common name in Westeros for the substance known as obsidian, a form of volcanic glass. They are notable for being thus far seen to be the only substance capable of killing White Walkers.
Grenn, Dolorous Edd, and Samwell Tarly find a cache of dragonglass spear heads along with an old warhorn buried in the snow on the Fist of the First Men. Sam identifies the material, but is unsure why it would have been left on the Fist by a ranger of the Night's Watch. Edd suggests that whoever it was, they wanted someone else to find the weapons.
After escaping Craster's Keep with Gilly, Sam shows her a piece of the dragonglass he had found. She asks what it does, and Sam responds that he isn't sure it does anything. He does remark how beautiful it is however. Sam later uses his dagger to slay a White Walker that was after Gilly's baby. When Sam stabs the White Walker in the shoulder, it turns to ice and shatters.
In the booksEdit
In the A Song of Ice and Fire novels, dragonglass is found in quantity on Dragonstone and in the ruins of Valyria, where it was used to make different kinds of ornaments, including candles. It is also an export from Asshai. According to legend, the Children of the Forest also made use of the substance. Samwell Tarly discovered, by chance, that dragonglass is one of the few materials that can harm or kill Others. According to legend, the Children of the Forest would provide the Night's Watch with weapons made of dragonglass specifically for that purpose.
Stabbing an Other with dragonglass will cause it to melt into a puddle of very cold liquid, not shatter to pieces. Samwell later stabs a wight with a dragonglass dagger, but discovers that it has no more effect on wights than regular swords do.
There are old notes claiming that Valyrian steel is also lethal to the Others, but so far it has not been put to test. Dragonglass is the only thing that was actually proved to be effective against the Others, not only in theory.
Dragonglass is sharper than steel, but also more brittle. For this reason it does not make good swords because they might shatter, but smaller daggers are more sturdy and therefore more common. They are also very effective as arrowheads.
In the books, it was Jon Snow who found the buried bundle. In it there were blades, a dozen knives, leaf-shaped spearheads, numerous arrowheads, and a broken warhorn.
Apart from its effectiveness against ice-bound evils and its use in magic, dragonglass is identical to real-world obsidian, down to its volcanic origins, its overall functional limitations, and its use as a reliable cutting tool by peoples who had yet to develop metallurgy. The World of Ice and Fire directly states that "obsidian" is what maesters officially call this type of volcanic rock, while "dragonglass" is a popular name for it used by the common people. That being said, it is almost always referred to as "dragonglass" in the novels, except for one or two points when a maester calls it "obsidian" (to point out to readers that "dragonglass" actually is "obsidian"). The Valyrian word for dragonglass translates as "frozen fire".