The most important aluminium compound known in homeopathy is not pure aluminium, but Alumina or aluminium oxide: Al2 O3.3H2O.
The name is derived from alumen or alum. It was discovered in 1872 and it is the most common metal and the third most common element on earth (7,5%). Aluminium is found in earth and clay.
The metal is very light and is used in aluminium foil and in aircraft. It is often used as a component in steel to bind the oxygen and to make it light in weight. Bearings usually contain magnesium, silicium, cuprum, zincum and zirconium (the latter is particularly used in spacecraft).