I'm not entirely sure what these metallic nodules are, save that they seem to come from the Wealden Clay formations on the UK's south-east coast, rather than the more familiar chalk. They are very distinct, being smooth with hints of banding rather than featuring obvious crystal structures. Nevertheless, I have seen them IDed as pyrite nodules, or possibly with haematite/goethite involved as well. Their smoothness is sometimes waterworn but can also be extremely shiny, suggesting the smoothness is original. 

You will receive the actual specimens photographed. Two standard-sized very round specimens, one very shiny, the other a little more waterworn. The shiny one has some pitting that I believe is intrinsic to the original stone structure. Each stone c4cm across.

These have been cleaned with a light abrasive nylon brush and treated with a little museum-grade Renaissance Wax. This slightly enhances and protects the surface, but it does not create a shine where there wasn't one before. Hence, I'm still regarding these as natural rather than polished.

Pyrites can be sensitive and some (not all) can succumb to pyrite decay when exposed to humidity in the air. I am not sure how stable these particular ones are. They have shown no sign of problems so far, but I've only had them for a few months and can't guarantee that there wont be issues in the future. For best results, it may be worth storing these in an airtight container with some silica gel. 

Specimens will be carefully packed in boxes with plenty of bubble wrap and fill.