Aluminum or tinned copper?
I looked and the silver color immediately told me aluminum, but the insulation looks older than the 60's or 70's. This house was built in 1903, originally wired with K&T, 60 amp service (so probably in the 20's or 30's). It had an addition put on in the late 50's.
It is also the only suspect wire in the entire panel - everything else is obviously copper.
I scratched it and it stayed the silver color.
I'm thinking this may be a leftover KT wire based on the insulation. Your thoughts please?
(For those that just say "Report what you see & move on" or something about reaching into a panel, this is in my house & I opened the main....I'm trying to learn something.)