From Longman Dictionary of Contemporary Englishgoldminegold‧mine, gold mine /ˈɡəʊldmaɪn $ ˈɡoʊld-/ noun [countable] 1 informalPROFIT a business or activity that produces large profits The nightclub turned out to be a goldmine.2 TIa place where gold is dug out from a hole in the ground3 → be sitting on a goldmine
Examples from the Corpus
goldmine• This was never well stocked and could hardly have been a goldmine.• It was the kiss that did for me, I think, not being called a goldmine.• I bet that corner shop's a goldmine.• It's just a scruffy little beach café, but in summer it's an absolute goldmine.• Consumerism, the modern goldmine and pipeline, roll merrily along.• It was loth to do this because the bonds were a potential goldmine when the junk-bond market recovered.• Manufacturers of computer-aided design systems are jockeying aggressively to take advantage of this potential goldmine.• His printing business has turned out to be a real goldmine.• One unfortunate woman who ran a discount shoe store was oblivious to the fact she was sitting on an old school goldmine.• Yet, in terms of potential, Sam had a shrewdness and a mind which was akin to an untapped goldmine.From Longman Business Dictionarygoldminegold‧mine /ˈgəʊldmaɪnˈgoʊld-/ (also gold mine) noun [countable]1informal a business or activity that produces large profitsPay-per-view television, under the right circumstances, is a proven gold mine.2be sitting on a goldmine to own something very valuable, especially without realizing itThe three companies realized they were sitting on a gold mine: a computerized directory containing the names and addresses of most people in America3a deep hole or system of holes under ground from which rock containing gold is takenThe Hayden Hill gold mine is expected to produce about 145,000 ounces of gold a year. 