Not a meteorite, here is why
the section you cut shows gas pockets, a meteorite would not have gas pockets,
meteorites which have been found that look like your specimen would have had olivine in those spaces which eroded away but since your cut is fresh and shows no olivine, it must be a gas...
That is also my opinion as to how the mine was found, so that would imply that the mine should be locatable by regular search methods.
this is important because it would have to place the mine in a location where gold would be expected to be, or....where a mine was able to be opened.
I recall...
May I chime in and ask a question?
did waltz use any clues when he found the mine the very first time?.......or, did he find the mine just by looking as would any prospector?
TYIA
I found something similar near some RR tracks as well, quite a few years ago. It was unbelievably heavy and left no streak. It turned out to be titanium ore.
apparently it fell off of a rail road car.
There is no way to tell by looking at your specimen, however it would be prudent to treat it as if it were a live round.
no hunk of rusty metal is worth your fingers.
you may want to look into fulminated mercury, it was used in warheads and becomes extremely sensitive with age, please do not...
OK, still, you said that Arthurs troops were not in Wales when the comet hit, they were in Normandy.
regardless if they were fighting or not, a camp of 70,000 would have been huge.
if they all were not in Normandy, and not in Wales....where were they?