Re: I'm reminded of early space exploration
It WAS Lead, once. I remember kids writing on slates (smoothed pieces of the roofing-material in a wooden frame) when I was one on the 1940s. Lead was used because it was malleable and easy to make a Point with, and could be wiped off. Pencils with graphite took over; someone wrote a book about that transition . . . Graphite came from a small outcrop in Cumbria, which suddenly became valuable.
(And ball-points came in because they could be used in swooping aircraft. LvS