|Geneva, Paris—Jean Charles Galissard de Marignac, Georges Urbain elements
Jean Charles Galissard de Marignac split terbia into terbia and (he called it) ytterbia, the oxide of ytterbium, the fourth element named after Ytterby, Sweden. * Years later, Georges Urbain isolated from ytterbium oxide two elements— neoytterbia, later named ytterbium, and lutecia, later named lutetium.
Atomic number 70
A little ytterbium-169 is a radiation source in portable X-ray machines. A little ytterbium improves the mechanical properties of stainless steel. A little ytterbium helps make an efficient laser with a short pulse.
Ytterbium occurs naturally as a mixture of seven isotopes. All seven exist in exceedingly small quantities. Exceedingly rare qualities, rare things matter a lot.