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

https://blogfreely.net/duerairjsl/salvo-metal-works-the-architects-partner-for-100-year-copper-chimney-shrouds

The series of alloys utilized is spectacular: weathering steel for aging, marine-grade light weight aluminum for weight cost savings, and duplex stainless for rust resistance in harsh climates.