protect it from air and moisture. All compounds of ytterbium are treated as highly toxic, although studies appear to indicate that the danger is minimal. However, ytterbium compounds cause irritation to human skin and eyes, and some might be teratogenic. Metallic ytterbium dust can spontaneously combust, and the resulting fumes are hazardous. Ytterbium fires cannot be extinguished using water, and only dry chemical class D fire extinguishers can extinguish the fires. References Further reading Guide to the Elements – Revised Edition, Albert Stwertka, (Oxford University Press; 1998) External links It's Elemental – Ytterbium Encyclopedia of Geochemistry - Ytterbium Chemical elements Chemical elements with face-centered cubic structure Lanthanides Suspected teratogens