Obsidian is volcanic glass formed by immense heat and pressure in the earth. 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. Some free folk carry dragonglass knives.
According to George R. R. Martin,
The children of the forest made tools and weapons out of dragonglass, including daggers, blades, and arrowheads. During the Dawn Age, the children 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.
In their war against the First Men, the children with their dragonglass weapons could not stand against the bronze weapons of the First Men. 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 shows a handful of arrowheads to Bran Stark, Rickon Stark, and Osha. Bran examines an arrowhead, noticing that the black glass is slick and shiny. He thinks it is beautiful, and asks 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. 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.
During Daenerys Targaryen's stay in Qarth, dragonglass from Asshai is among the gifts she receives from people seeking to learn the truth behind the rumors about living dragons. The dragonglass is among the many offerings Daenerys sells to gather the wealth she ends up wasting on the Pureborn. After the death of the Undying Ones, Xaro Xhoan Daxos tells Daenerys that glass candles that have not burned in a hundred years are now burning in the house of Urrathon Night-Walker.
A Storm of Swords
Samwell and the few survivors from the fight at the Fist escape 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. 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 of the Night's Watch 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 which was once 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 Ser Rolland Storm, the castellan of Dragonstone, to begin mining obsidian on the volcanic isle.
A Feast For Crows
In Oldtown, Leo Tyrell tells his fellow acolytes and novices of the Citadel 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.
At the Wall, Samwell tells Jon, the new Lord Commander, that he has learned the children of the forest used to give the Night's Watch a hundred obsidian daggers every year, during the Age of Heroes.
A Dance With Dragons
Luwin: 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 mail, they wore long shirts of woven leaves and bound their legs in bark, so they seemed to melt into the wood. In place of swords, they carried blades of obsidian.
Osha: And still do.
Samwell: The m-maesters think not. The maesters say it comes from the fires of the earth. They call it obsidian.Jeor: They can call it lemon pie for all I care. If it kills as you claim, I want more of it.
- A Feast for Crows, Prologue.
- A Clash of Kings, Chapter 34, Jon IV.
- A Storm of Swords, Chapter 33, Samwell II.
- A Storm of Swords, Chapter 78, Samwell V.
- "Interview with the Dragon" © 2003 Robert Shaw
- A Game of Thrones, Chapter 66, Bran VII.
- A Clash of Kings, Chapter 43, Jon V.
- A Feast for Crows, Chapter 45, 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 Dance with Dragons, Chapter 53, Jon XI.
- A Dance with Dragons, Chapter 58, Jon XII.
- A Storm of Swords, Chapter 18, Samwell I.
- A Game of Thrones, Chapter 34, Catelyn VI.
- A Clash of Kings, Chapter 16, Bran II.
- A Clash of Kings, Chapter 37, Theon III.
- A Feast for Crows, Prologue.
- A Clash of Kings, Chapter 27, Daenerys II.
- Fire & Blood, A Surfeit of Rulers.
- A Game of Thrones, Chapter 48, Jon VI.
- The World of Ice & Fire, Ancient History: The Dawn Age.
- The World of Ice & Fire, Dorne: The Breaking.
- A Feast for Crows, Chapter 5, Samwell I.
- A Dance with Dragons, Chapter 33, Tyrion VIII.
- The World of Ice & Fire, Ancient History: The Doom of Valyria.
- A Clash of Kings, Chapter 63, Daenerys V.
- A Storm of Swords, Chapter 46, Samwell III.
- A Dance with Dragons, Chapter 11, Daenerys II.
- A Dance with Dragons, Chapter 35, Jon VII.