Profitable venture

• Treasure trove, figuratively
• Source of sudden wealth
• Source of valuable metal
• Bonanza
• Source of great wealth
• Source of great wealth, or a potential danger

Wikipedia Word definitions in Wikipedia
Gold mining is the process of mining gold or gold ores from the ground. Goldmine or gold mine may also refer to: Gold Mine (board game) , a tile-laying board game Goldmine (magazine) , a music collectables magazine Goldmine (album) , an album by Silvia ...

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, ...