After oxygen and silicon, aluminium is the third most frequent element making up 8% of the lithosphere. Due to its strong affinity with aerator, aluminium only exists as a compound not in a solid form in the nature. The primary product for the production of aluminium is bauxite, a weathering product consisting of limestone and silicate stone, usually with a high content of Al2O3 (alumina), more than 50%.

Metallurgic aluminium is split into two groups: the normalised materials possessing a consistency which is achieved by mixed crystallisation and the thermosetting materials possessing a consistency which is achieved by eliminating formerly dissolved alloying components. The normalised alloys are used instead of pure aluminium in case a higher consistency with high extension limits is needed. The highest consistency values are achieved for thermosetting alloys. The corrosion resistance for these alloys is, however, less than for normalised materials.

 Further information about aluminium:

Aluminium on Wikipedia