(1) The addition of small amounts of osmium to these metals greatly increases their hardness.(2) Scientists speculate that the asteroids would probably be very rich in minerals with a very high melting point, such as iron and nickel or rarer metals like tungsten, osmium , and zirconium.(3) With the exception of two of the platinum-group metals, osmium and iridium, they have the highest melting temperatures and lowest vapor pressures of all metals.(4) Along with osmium and platinum, iridium is one of the densest elements in the periodic table: two cubic feet of it weigh as much as a Buick.(5) Other examples of relative isotopic dating are the deuterium variations in ice cores and the osmium isotope record of marine sediments.
