I don’t think X-rays would penetrate very far into a gold bar.
Of course you are right. Still, there must be some kind of acoustic means, like seismologists use. With some kind of gear, that Au/K transition will stick out like a sore thumb.
151 posted on 11/15/2009 3:50:45 PM PST by Atlas Sneezed
(“Personal freedom begins when you tell Old Mrs. Grundy to go to Hell.” -Lazarus Long)