Beryllium is the chemical element with the symbol "Be" and atomic number 4. Because any beryllium synthesized in
stars is short-lived, it is a relatively rare element in both the universe and
in the crust of the Earth. It is a divalent element which occurs naturally only in
combination with other elements in minerals. Notable gemstones which contain
beryllium include beryl (aquamarine, emerald)
and chrysoberyl. As a free element it is a
steel-gray, strong, lightweight and brittle alkaline earth
metal.
Beryllium
increases hardness and resistance to corrosion when alloyed to aluminium, cobalt, copper (notably beryllium copper), iron and nickel. In
structural applications, high flexural rigidity, thermal stability, thermal
conductivity and low density (1.85 times that of water) make
beryllium a quality aerospace material for high-speed aircraft,missiles, space vehicles and communication
satellites. Because
of its low density and atomic mass, beryllium
is relatively transparent to X-rays and other forms of ionizing
radiation; therefore, it is the most common window material for
X-ray equipment and in particle physics
experiments. The
high thermal conductivities of beryllium and beryllium oxide have led to their use in heat transport and heat sinking applications.
The
commercial use of beryllium metal presents technical challenges due to the toxicity (especially
by inhalation) of beryllium-containing dusts. Beryllium is corrosive to tissue,
and can cause a chronic life-threatening allergic disease called berylliosis in
some people. The element is not known to be necessary or useful for either
plant or animal life.
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