impurities

elements in the crystal structure that are foreign to the basic chemical composition of the gem.
Found on http://gemologyproject.com/wiki/index.php?title=Glossary_of_Terms

impurities

<radiobiology> Atoms (or ions) of unwanted elements in the plasma, which tend to degrade plasma performance, and in the case of fusion plasmas tends to inhibit fusion (poisoning the reactor). ... See: poisoning. ... (09 Oct 1997) ...
Found on http://www.encyclo.co.uk/local/20973

Impurities

Any nongrain material contained within a shipment that could hinder the processing of a grain or detract from its end value.
Found on http://www.hotgrain.com/glossary
No exact match found