Answer:

rhodium

AnswerCrossword Clue
RHODIUMElement used in electroplating
RHODIUMElement No. 45.
RHODIUMHard chemical element.
RHODIUMRelative of platinum.
RHODIUMRare element in platinum ores
RHODIUMMetal used in mirror coating
RHODIUMPlatinum family element