emerald and diamond nuggets for archaeology

Currently only gold and iron nuggets exist in archaeology, whereas diamonds and emeralds appear as their entire metal. It would fit the theme of archeology better to also have nuggets for emerald and diamond as well, as archaeological remains are ancient. Also, it would be consistent with gold and iron coming in the form of a nugget. Finally, it would balance archaeology better if emerald and diamond were found not as entire metals but instead nuggets.