I just watched Indiana Jones and the Kingdom of the Crystal Skull, and I’m baffled. Early in the movie — yes, there are spoilers ahead, but nothing major — Indy is held captive in an Air Force hanger in Area 51, and his captors demand his help in finding a particular crate — not the one with the Ark, by the way.
Indy declares that the crate they’re looking for has highly magnetic contents and demands a compass to help find it. The soldiers holding him captive have no compasses. So he demands… gunpowder?
There’s nothing ferrous about gunpowder — the nitrocellulose and nitroglycerin in modern smokeless powder have no iron, and neither does old-fashioned blackpowder, which is charcoal, sulfur, and saltpeter — so I assume Indy is setting up some kind of ruse. I’m just upset that his captors are being played for fools. He throws the powder in the air, and it starts floating in a trail through the warehouse. What is it really?, I’m thinking.
Then he demands a shotgun shell and some pliers. I’m a bit surprised that his captors have a shotgun — they’re soldiers, not hunters — and that they’re still playing along, but OK. Then he breaks open a shell, and the lead pellets — shotgun pellets are normally lead, which is not ferrous, in case you were wondering — race toward one of the crates.
His captors then open the crate, and various ferrous things — lamps hanging from the ceiling, the villain’s sword, etc. — finally start getting pulled toward the highly magnetic contents. But the soldiers’ assault rifles aren’t generally affected.
Huh?
Later in the film they find a similar relic, which attracts gold — inconsistently — and they seem to recognize that as not quite magnetism.
And those were some of the less implausible elements of the story. You can tell the screenplay passed through a number of hands before getting produced.