Job 19:24

That they were graven with an iron pen and lead in the rock for ever!

Pen - graver.

Lead - poured into the engraven characters, to make them better seen (Umbreit). Not on leaden plates; because it was "in the rock" that they were engraved. Perhaps it was the hammer that was of "lead," as sculptors find more delicate incisions are made by it than by a harder hammer. Forster ('One Primeval Language') has shown that the inscriptions on the rocks in Wady-Mokatta, along Israel's route through the desert, record the journeys of that people, as Cosmas Indicopleutes asserted, 535 AD Whether his view be correct or not, the engraving of inscriptions on rocks is of very ancient date.

For ever. As long as the rock lasts; not perishable as a "book" (Job 19:23) would be.