 These metals share qualities of extreme hardness and corrosion resistance.The tipping material is often called "iridium", but there are few if any, nib or pen manufacturers that used tipping alloys containing iridium metal since the mid-1950s.The metals osmium, rhenium, ruthenium and tungsten are used instead, generally as an alloy, shaped into tiny pellets which are soldered or welded onto a nib tip prior to cutting the nib slit and grinding the tip into its final shape.