Dragonglass is the name used by the smallfolk for a volcanic glass which the maesters of the Citadel call obsidian. Obsidian was used by the children of the forest to fabricate weapons. The Valyrians called obsidian frozen fire and made use of obsidian to make their glass candles. The smallfolk like to say that dragonglass is made by dragons, while maesters say it comes from the fires of the earth.
There are large deposits of dragonglass on Dragonstone. It is an export product from Asshai, and possibly the Shivering Sea, while the Skagosi trade obsidian blades and arrowheads. Obsidian blades are sharper than steel but far more brittle.
Dragonglass weapons are one of the few weaknesses of the Others. An Other that is pierced by an obsidian blade dies almost instantaneously.
According to George R. R. Martin, he has given obsidian,
The children of the forest made weapons out of dragonglass, including daggers, blades, and arrowheads. During the Dawn Age, the children of the forest fought against their greatest foes, the giants, with obsidian weapons, as possibly proved by Maester Kennet, whose study describes a giant's burial at a barrow near the Long Lake, who had obsidian arrowheads amidst his extant ribs. During the Age of Heroes, it was recorded by the Night's Watch that the children of the forest gave the black brothers a hundred obsidian daggers every year.
A Game of Thrones
In his turret in Winterfell Maester Luwin pours a handful of shiny black arrowheads out of a green jar and shows them to Bran Stark, Rickon Stark, and Osha. Osha names the material dragonglass, and Maester Luwin tells them that it is obsidian; he says that the children of the forest worked no metal and hunted with obsidian instead, and in place of swords they carried blades of obsidian. Osha remarks that they still do. Bran examines the arrowhead, noticing that the black glass is slick and shiny. He thinks it's beautiful, and asks Maester Luwin if he can keep one.
A Clash of Kings
At the Fist of the First Men, Jon Snow discovers a cache of knives, leaf-shaped spearheads, and numerous arrowheads made of obsidian. Dragonglass, he thinks to himself. Beneath the dragonglass is an old warhorn, and when Jon shakes the dirt from inside it, a stream of arrowheads falls out. Jon gives Samwell Tarly a spearhead and a dozen arrowheads as well, and passes the rest out among his other friends for luck.
As Daenerys Targaryen enters Qarth, she passes under a bronze arch depicting two snakes mating, whose scales are made of jade, obsidian, and lapis lazuli. During her stay in Qarth, Daenerys receives multiple gifts from people seeking to learn the truth behind the rumors about living dragons. These gifts include dragonglass from Asshai. The dragonglass is among the many offerings Daenerys sells, to gather the wealth she ends up wasting on the Pureborn.
A Storm of Swords
Samwell Tarly and the few survivors from the Fist are escaping south, with a heavy snow falling. Upon an undead horse, a lone Other appears. In a blind panic, Sam slays the Other by stabbing it with the dragonglass dagger given to him by Jon Snow. The dagger causes the Other to shrink and puddle, dissolving away in twenty heartbeats. Only the dagger remains, wreathed in steam. Grenn goes to scoop up the dragonglass dagger, but has to fling it down again as it is extremely cold.
At Craster's Keep, Samwell discusses obsidian with Jeor Mormont. The Lord Commander tells Sam that if dragonglass kills the Others as Sam claims, he wants more of it. Sam remarks that the children of the forest would know where to find obsidian, but Lord Commander Mormont tells him that the children are all dead.
Sam and Gilly, escaping from the mutiny at Craster's Keep, are menaced by a wight, what remains of Small Paul. Sam attempts to stab him with the dragonglass dagger, but it shatters upon contact with Paul's chainmail.
At the Wall, after hearing about the properties of dragonglass from Sam, King Stannis Baratheon sends word to his castellan Ser Rolland Storm on Dragonstone to begin mining obsidian. He fears he will not hold his seat much longer but hopes that the Lord of Light shall grant them enough frozen fire to arm themselves against the Others before the Dragonstone falls.
A Feast For Crows
In Oldtown, Leo Tyrell tells his fellow Citadel acolytes and novices that there is a glass candle burning in Archmaester Marwyn's chambers. Armen explains the vigil an acolyte must hold to become a maester, where one fruitlessly attempts to light one of the Citadel's glass candles, and says that obsidian does not burn. Pate remembers that the smallfolk call obsidian dragonglass, and Alleras wonders if the return of dragons is what lets the candle burn again.
A Dance With Dragons
Obsidian. Forged in the fires of the gods, far below the earth. The children of the forest hunted with that, thousands of years ago. The children worked no metal... In place of swords, they carried blades of obsidian.—Maester Luwin
- A Feast for Crows, Prologue.
- A Clash of Kings, Chapter 34, Jon IV.
- A Storm of Swords, Chapter 33, Samwell II.
- A Game of Thrones, Chapter 66, Bran VII.
- A Feast for Crows, Chapter 45, Samwell V.
- A Storm of Swords, Chapter 78, Samwell V.
- A Clash of Kings, Chapter 40, Daenerys III.
- A Storm of Swords, Chapter 54, Davos V.
- The World of Ice & Fire, The North: The Stoneborn of Skagos.
- A Clash of Kings, Chapter 43, Jon V.
- "Interview with the Dragon" Copyright © 2003 Robert Shaw.
- The World of Ice & Fire, Ancient History: The Dawn Age.
- A Feast for Crows, Chapter 5, Samwell I.
- The World of Ice & Fire, Dorne: The Breaking.
- The World of Ice & Fire, Ancient History: The Doom of Valyria.
- A Clash of Kings, Chapter 16, Bran II.
- A Clash of Kings, Chapter 27, Daenerys II.
- A Clash of Kings, Chapter 63, Daenerys V.
- A Storm of Swords, Chapter 18, Samwell I.
- A Storm of Swords, Chapter 46, Samwell III.
- A Dance with Dragons, Chapter 11, Daenerys II.