Board Thread:Suggestions Forum/@comment-26295802-20150409224618/@comment-26298013-20150410125814

I believe that you are thinking of the moon-runes of the Dwarves, written with silver pens of...something. Probably ithildeen or a Mithril mixture similar to it, seeing as how the Elves made ithildeen out of Mithril. The Dwarves, of course, primarily used Mithril as a metal, because they could make a metal out of it.

But maybe, in order to keep these runes from being too expensive, you could just use normal silver instead of Mithril. Because Mithril is, indeed, far too expensive for players to use to write cryptic, moon-visible messages that nobody else really cares about. Dwarves in the books, however, got large(ish) veins of the stuff. We just get pockets.