What is the value of a 1879 goloid metric silver dollar?

What you have is an example of a pattern, or experimental, coin made to test an alloy alloy of silver, gold and copper being proposed as a way to reduce the rather cumbersome size of silver dollars. It was ultimately rejected due to concerns about counterfeiting.

I used the Word "example" because it's unlikely your coin is genuine. Only a few actual patterns are known to exist, while there are numerous copies. Unless you can find the small Word "COPY" worked into the design somewhere (required by law since the 1970s) the only way to tell whether or not it's real would be to have it tested by a coin expert.

so does that mean if it is not real the Words copy would be found on it?