Is an 1877 US dollar silver?

Answer 1

The only silver-dollar sized coins struck in 1877 were Trade Dollars. These coins were made of the same 90% silver alloy as standard silver dollars, but were slightly larger and heavier. They were stuck specifically for use in international trade.

A few thousand gold $1coins were also struck in 1877. Their alloy was 90% gold but it included a very small amount of silver and copper for hardness.