Galvorn was a metal devised by Eöl from which he made resistant armor. Black and "shining like jet", it was hard as steel, but supple and malleable, proving resistant to all blades and darts.
It's possible that galvorn was forgotten or lost with Eöl's death, as it was not mentioned in the later Ages.
The word galvorn translates as "shining black" in Sindarin. It is formed by combining gal, which means "shine" and morn, signifying "dark" or "black".
 Other versions of the legendarium
The original name of galvorn was rodeöl, the metal of Eöl. J.R.R. Tolkien changed this many times, to glindûr, targlîn, morlîn, back to glindûr, and then maeglin. Finally galvorn was chosen.
- ↑ J.R.R. Tolkien, Christopher Tolkien (ed.), The Silmarillion, "Quenta Silmarillion: Of Maeglin"
- ↑ Robert Foster, The Complete Guide to Middle-earth, p. 157, entry "Galvorn"
- ↑ "Compound Sindarin Names in Middle-earth" at Tolkiendil.com (accessed 8 June 2011)
J.R.R. Tolkien, Christopher Tolkien (ed.), The War of the Jewels, "Part Three. The Wanderings of Húrin and Other Writings not forming part of the Quenta Silmarillion: III. Maeglin", pp. 322-323