Treasure trove, figuratively

• Source of wealth
• Bonanza
• Source of great wealth, or a potential danger
• Profitable venture

Wikipedia Word definitions in Wikipedia
" Goldmine " is a song recorded by Canadian country music artist George Fox . It was released in 1989 as the fourth single from his debut album, George Fox . It peaked at number 9 on the RPM Country Tracks chart in August 1989.

Longman Dictionary of Contemporary English Word definitions in Longman Dictionary of Contemporary English
noun EXAMPLES FROM OTHER ENTRIES ▪ His printing business has turned out to be a real 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 . EXAMPLES FROM CORPUS ▪ Consumerism, ...