From A Wiki of Ice and Fire
Dragonstone is a building material used by the Valyrians in much of their construction. It is harder than iron, steel, granite or diamond. It is believed the Valyrians used magic or dragonflame to work the stone, turning it into liquid before shaping and fusing it.
The castle of Dragonstone, the dragonroads, the inner walls of Tyrosh, the Black Wall of Volantis, and the ruins of a Valyrian fort in Naath are all made of fused black dragonstone.
- ↑ 1.0 1.1 The World of Ice & Fire, The Seven Kingdoms: The Reach: Oldtown.
- ↑ 2.0 2.1 The World of Ice & Fire, The Free Cities: Volantis.
- ↑ The World of Ice & Fire, Ancient History: The Doom of Valyria.
- ↑ A Storm of Swords, Chapter 10, Davos II.
- ↑ 5.0 5.1 The World of Ice & Fire, The Reach: Oldtown.
- ↑ The World of Ice & Fire, The Free Cities: The Quarrelsome Daughters: Myr, Lys, and Tyrosh.
- ↑ The World of Ice & Fire, Beyond the Free Cities: Naath.