Hrm ... well, I do know rust doesn't conduct electricity very well. How good an insulator it is depends on the voltage, and how good a coverage it is.
Your real question, where to look this up on your own, that I can't answer. For rust, I kinda always knew it. Why do we clean the oxide coating off of any metal? Because, if it is to be useful as a conductor, it has to be clean. Now, scrape little 8 year old Arkcon*, until you can see your refection in it. Basically, any general science text may tell you, that the oxide coating of a metal surface needs removal, for most applications.
Perhaps, if you read a general chemistry book, for the definition of metal, and the definition of what we call compounds of the type iron oxide, you might discover a hint to use next time.
*Disclaimer: my parents did not actually name me Arkcon, they are not that cruel