Aluminum is a silvery white member of the boron group of
chemical elements. It has the symbol Al, and its atomic
number is 13. It is not soluble in water under normal
Aluminum is the third most abundant element (after oxygen
and silicon), and the most abundant metal, in the Earth's
crust. It makes up about 8% by weight of the Earth's solid
surface. Aluminum metal is too reactive chemically to occur
natively. Instead, it is found combined in over 270
different minerals. The chief ore of aluminum is bauxite.
Aluminum is remarkable for the metal's low density and for
its ability to resist corrosion due to the phenomenon of
passivation. Structural components made from aluminum and
its alloys are vital to the aerospace industry and are
important in other areas of transportation and structural
materials. The most useful compounds of aluminum, at least
on a weight basis, are the oxides and sulfates.
Despite its prevalence in the environment, aluminum salts
are not known to be used by any form of life. In keeping
with its pervasiveness, aluminum is well tolerated by plants
and animals. Due to their prevalence, potential
beneficial (or otherwise) biological roles of aluminum
compounds are of continuing interest.