(bĕ-rĭl′ē-ŭm)
[Pronunciation]
[Gr. beryllos, beryl]

A metallic element, symbol Be, atomic weight 9.0122, atomic number 4, specific gravity 1.848.
It is used as a window in some x-ray tubes to produce a soft (low kilovoltage) beam appropriate for imaging soft tissue (mammography or specimen radiography) or for forensic and industrial radiography of extremely thin objects (e.g., a postage stamp or fingerprint).