The variety of alloys made use of is stunning: weathering steel for patina, marine-grade light weight aluminum for weight cost savings
https://www.scribd.com/document/1039773992/Finials-That-End-Up-Well-100-Years-of-Copper-Integrity-146161
The series of alloys made use of is magnificent: weathering steel for aging, marine-grade aluminum for weight financial savings, and duplex stainless for deterioration resistance in harsh climates.