I might misremember, but wasn't there something about the use of aluminum flakes in resin for verification in disarmaments, i.e., use a blob of flakes in resin

I might misremember, but wasn't there something about the use of aluminum flakes in resin for verification in disarmaments, i.e., use a blob of flakes in resin to mark and then check the pattern when about to be scrapped? Could have been just a concept many years back, though. Certainly powerful stuff as very difficult to reproduce at any kind of scale.