Answer
Copper and Nickel (Cupronickel Contains a High Percentage of Copper Usually Somewhere Between 60 and 90 Percent and Sometimes Iron and Manganese is Added for Extra Strength. Cupronickel is Highly Resistant to Salt Water Corrosion and as a Result is Mainly Used in Marine Hardware But it is Also Used for Coins and it is Ocassionally Refererred to as Hotel Silver)