a person, book, etc. that can give you a lot of information on a particular subject
A MINE OF INFORMATION (ABOUT / ON SB/STH)
Meaning of A MINE OF INFORMATION (ABOUT / ON SB/STH) in English
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005