Germanium [Ge]

A greyish-white semi-metal of density 5.23 g/cc and melting point 940 degC, expanding on solidification.  It is abundant in nature but not in high concentrations.  Germanium is brittle and resembles tin chemically but with silicon-type physical properties. 

Its electrical properties are of a semi-conducting nature and it aids corrosion resistance in electronic applications.  It is used in infrared and fibre optics, solar cells, catalysis, and it hardens gold.

Found as traces in coal and certain zinc ores and is recovered from their processing flue deposits.  These are purified many times to reach very high levels.

It is traded in the form of bars and single crystals with min 5N purity expressed in terms of its electrical resistivity – typically <50 ohms/cm.

Quantities are quoted in 100’s of kg.