He should be a gold mine of information for them.

I might, she told herself, be looking at a gold mine.

He'd found a gold mine and didn't want anyone to know about it.

There's a gold mine further down, which you can just make out from here.

The deal with the Met could make a gold mine of this site.

This was like no gold mine he had ever heard of.

Sure, that guy knows a lost gold mine he's going to offer us.

This is a little gold mine we've got going here.

For students of popular culture the material is a gold mine.

For all this, however, the place is not yet a gold mine.