Today, lead pencils contain a mix of graphite and clay, in ratios chosen to produce varying "darkness" of the marks. Higher graphite content is softer, darker, and wears more quickly.
The traditional classification scale runs from 9B ('B' for blackness) down to 1B, HB, F (for fine, or firm, but not meaningful really), 1H, and up to 9H ('H' for hardness). HB is the US-typical "#2 pencil".
https://www.britishmuseum.org/collection/object/P_1860-0616-...
Really looks like modern (graphite) pencil, doesn't it? (Unless I've misunderstood which parts are lead and which aren't -- but I think I've interpreted it right).
edit: Here's a technical article about how you can positively identify lead (Pb) in medieval drawings, and distinguish it from silver and other metals. (In case anyone was still skeptical). They show a variety of other examples.
https://sci-hub.se/10.1179/sic.2009.54.2.106 ("A Note on the Examination of Silverpoint Drawings by Near-Infrared Reflectography")
Anecdote: In ~5th grade science class, we had a folded sheet of metallic lead that was passed around for students to handle. I suspect this practice has been discontinued!
At the time, I thought pencils contained real lead (Pb), so I tried to use the lead sheet to mark paper. It worked well! But not as well as (and had different marking characteristics from) a regular pencil. I assumed the improvements were part of the productization, but that the pencil still used real lead.
Wikipedia says, on the discovery of naturally-occurring graphite:
> Chemistry was in its infancy and the substance was thought to be a form of lead. Consequently, it was called plumbago (Latin for "lead ore").
It's funny how names stick. 500 years and counting on this one.
