goldmine
noun [ C ]
NATURAL RESOURCES uk/ˈɡəʊldmaɪn/ usa place where gold is taken from the ground
something from which a person, company, etc. can earn a lot of money or that can provide a lot of something that people want:
Manufacturers of computer-aided design systems are competing to take advantage of this potential goldmine.
a goldmine of sth There's a goldmine of multimedia information at the site.