http://grammarist.com/spelling/aluminium-aluminum/
Aluminium vs aluminum
Aluminum is the American and Canadian spelling for the silver-white metallic element (number 13 on the periodic table) abundant in the earth’s crust.
Aluminium is the preferred spelling outside North America. Neither term is superior to the other, and both are etymologically and logically justifiable. Aluminum is older, while
aluminium is more consistent with other element names such as helium, lithium, magnesium, and so on (though let’s not forget there are other -um elements - molybdenum, tantalum, and platinum).
Aluminium has the edge in scientific writing even in North America. This is primarily because several influential scientific organizations and publications prefer the spelling.