Where can I find a list of active mining claims in my area (Northern Nevada)? I live in the Reno/Sparks area and have started rockhounding.  One aspect I am quickly realizing is that many sites are actively being mined.  In order to avoid running afoul of local laws, I would like to get a map of active mining claims and potentially a map of expired claims.  Expired claims would be helpful for finding interesting sites.
You may want to check this out ESRI open data http://opendata.arcgis.com/ if this is what you were looking for.

One another thing is that you might want to contact BLM's Nevada State Office.

http://www.blm.gov/nv/st/en/prog/minerals/mining.html

They may have the data if they are on the Public lands. I am not sure about the private lands for that.