The variety of alloys used is stunning: weathering steel for patina, marine-grade aluminum for weight savings

https://magic-wiki.win/index.php/The_Honest_Material:_Why_Architects_Count_On_Copper_Dormers_for_Long-Horizon_Design

The series of alloys used is stunning: weathering steel for patina, marine-grade aluminum for weight cost savings, and duplex stainless for deterioration resistance in severe environments.