Metalpoint is an interesting medium. The stylus is silver (or gold, copper, brass, etc.) instead of graphite. This method dates long before graphite was discovered and used. I bought a set of two silverpoint pens, one with a thin stylus and one thick. I’m sketching on mineral paper. Plain paper won’t catch the metal, and so the surface needs to be prepared with gesso or something along those lines. Mineral paper, however, is a fine metalpoint surface on its own.
It’s a slower process than using a pencil, but the effect is light, airy, and shimmery. It doesn’t smudge and lasts for a very long time. Some metals tarnish, and this silver sketch of my horse will probably turn sepia as time goes by.