Black nails are a type of nail in RuneScape. They are used in the Construction skill to make certain furniture, and can also also be hammered onto flighted ogre arrows to create black brutal arrows, requiring 38 Fletching and granting 6.5 experience.
Unlike other nails, they cannot be made with the Smithing skill. They are a possible piece of loot from Zogre coffins. They may also be obtained while clearing rubble during the In Aid of the Myreque quest. You can also get them as a drop from zombies in Tarn's Lair.