Atomic number 4, beryllium is an earth metal element that is only found in nature combined with other elements. Common examples include gemstones such as aquamarines and emeralds. It was discovered in 1798 by Louis-Nicolas Vauquelin, and isolated in 1828. It is chemically similar to aluminum. It has a very high melting point and resists oxidation in the air.
Beryllium is used in alloys with other metals, such as copper, where it acts to harden the alloy. It is used in X-ray tubes, and, because of its stiffness, light weight, and stability, in the aerospace and satellite industries. It is also employed where non-magnetic tools must be used. It is toxic when inhaled, and is corrosive to skin and other tissues. It can produce an allergic reaction in some people.
In the pro audio industry, beryllium is used by manufacturers such as Focal for constructing high-frequency dome drivers. According to Focal, Beryllium is seven times more rigid than titanium or aluminum, and propogates sound waves three times faster than the former and 2.5 times faster than the latter. This provides more linear frequency response and better impulse response.