TWO INTERESTING METALS: PALLADIUM AND NIOBIUM, AND HOW ABOUT ZENOBIUM?

The Master Marker at the Edinburgh Assay Office advises me that he has marked a silvery white metal called ZENOBIUM (or XENOBIUM) which can change colour. I have however been unable to trace this metal anywhere on the Internet. Does anybody know which of the metallic elements he is referring to?

                                                                           

                                                            PALLADIUM



                                                                     

                                                            NIOBIUM