Lee Bennett:

In evaluating historic mines you might want to refer to Nation Register
Bulletin 42, Guidelines for Identifying, Evaluating, and Registering
Historic Mining Properties.

In understanding the resource from a systems approach you might want to try
The Archaeology of Mining and Miners: A View from the Silver State, Special
Publication Series, #6, Society for Historical Archaeology (Don Hardesty
1988).

Since you have resources that are less than 50 years (?) you might want to
consult National Register Bulletin 22, Properties that have Achieved
Significance within the Past Fifty Years.

I get the impression from your listing that you have several mines in a
single drainage.  Instead of evaluating each property separately you might
want to consider the collective whole as a mining district.  The whole
might be more important than the individual parts, the parts contributing
to whole - you get the idea.

Sounds like a great project.  Good luck.......ww