What does it mean if someone is a "minefield of information"

Solution 1:

Minefield is often used figuratively to refer to something dangerous – to something that may seem harmless, but really isn't. NOAD reads:

minefield (figurative): a subject or situation presenting unseen hazards : a minefield of technical regulations.

There's also a common idiom: he knows just enough to be dangerous, which is used when someone has just a little bit of knowledge about something, but is not very proficient. That little bit of knowledge can give a person a false sense of confidence that can eventually lead to trouble. (For example, if you know a little bit about engines, you might start taking one apart, only to find out you're not going to fix the engine – and you might even have trouble putting it back together again.)

Minefield of information is not an established idiom; it might have been misspoken, misheard, or else it's someone trying to say something humorous, playing off of mine of information, which is used to refer to a person or database where much valuable information can be gleaned. If that information is sometimes faulty, one might say something like:

Watch out for Wikipedia! It's a minefield of information.

which I think reads rather clever, but it's not an established idiom. That said, it's not completely original, either; others have used it.

Solution 2:

The idiom I'm used to is "a gold mine of information about X," meaning someone who's willing and able to tell you a whole bunch about X. Here's a (not very detailed) verifying link.

Solution 3:

This is rather late in the day for the question, but I only now stumbled upon this thread...

The expression "minefield of information" may be a reference to an Afrikaans novel, "Griet Skryf 'n Sprokie" by Marita van der Vyver (apparently "Entertaining Angels" in English). In it, the protagonist at one point tells her best friend, after he (as is typical for him) told her an obscure fact:

You're a veritable minefield of useless information - I never know when the next explosion is going to hit me ^{[translation from the German version mine, quoted from memory]}

This is pretty self-explanatory, I suppose. I always thought it a rather clever image - but of course it only makes sense if the second part isn't left out.