osmiridium: a hard and corrosion resistant mineral that is a natural alloy of osmium and iridium (usually containing small amounts of rhodium and platinum); used in needles and pen nibs etc.
substance: the real physical matter of which a person or thing consists
art nouveau: a French school of art and architecture popular in the 1890s; characterized by stylized natural forms and sinuous outlines of such objects as leaves and vines and flowers