Aluminum oxide is an extremely hard man-made material (used in grey sandpaper for instance). Particles of aluminum oxide suspended in the factory finishes of wood flooring greatly increase abrasion resistance and allow for wear-through warrantees not yet available from finishes applied at the jobsite to unfinished flooring.
Added to the urethane finish for increased abrasion resistance of the wear layer, which is becoming extremely popular on the better grade wood floors.
A chemical compound of aluminum with oxygen, which forms immediately on an unprotected aluminum surface exposed to air. Aluminum Oxide does not flake off, but forms a protective layer that blocks further oxidation and so protects the integrity of the metal. It is transparent and does not alter the appearance of the aluminum surface.