The range of alloys used is spectacular: weathering steel for patina, marine-grade light weight aluminum for weight cost savings

https://source-wiki.win/index.php/The_Reality_in_the_Aging:_Why_Custom-made_Finials_in_Copper_Are_the_Designer%27s_Time-Tested_Selection

The range of alloys made use of is stunning: weathering steel for patina, marine-grade aluminum for weight financial savings, and duplex stainless for corrosion resistance in severe environments.