Note: ☞ Iridium usually occurs as a native alloy with osmium ( iridosmine or osmiridium), which may occur alone or with platinum. Iridium, as an alloy with platinum, is used in bushing the vents of heavy ordnance. It is also used for the points of gold pens, and in a finely powdered condition ( iridium black), for painting porcelain black.
Etymology: NL., fr. L. iris iridis, the rainbow. So called from the iridescence of some of its solutions. See Iris