pure (raw) metals VS oxidized metals metallicity

[YuriKruglov]

Please consider the possibility of making clarifications regarding the metallicity values ​​of pure and oxidized metals in database of physically based values for CG artists. It should be noted that the values ​​given in the table do not take into account oxidation and presented for pure (raw) metals. In real world in an oxygen environment pure (raw) metals like aluminium or copper quickly become covered with an oxide film and the metallicity of their surface becomes not 1.

PBR Guide - Wes McDermott, allegorithmic, 2018
Unreal engine documentation
Unity documentation