Conglomerate

Son M and I once found a treasure site, using two metal detectors. Strangely, our metal detectors started to scream -- not the usual signal one receives. We discovered that it was conglomerate, over a large area. The photo gives an impression of what that is. One sees a brass screw in it (top right), and brass pins (bottom left). In fact it is "riddled" with metal: iron, brass, copper, gold. OBSERVATION: We were the first to register this find, though not the first to know about it. That first day, we found a gold coin there -- but it was a long time before we found another one.