Well here I am detecting and digging through bent twisted aluminium bits, copper plates with rivets, chunks of plexi glass and I get another good signal; turns out to be a 2 Reales Philips III (1598-1621)! Was hoping to find parts that would ID the aircraft, but no luck so far. Have found two items that look like radio buttons that have numbers on the back.
The detector is going mad all over the place, mainly on chunks of cast aluminium from the engine(s). Never thought I would unearth a silver 17th century cob coin between the rubble!
It weights 6,76 grams.