Refers to a mine where gold is extracted. Can also be used figuratively for a very profitable source.
See also: 金山 (かなやま)
A gold mine was discovered in California in the 19th century.
There used to be a gold mine in this area.
That new business is a gold mine for the company.
His grandfather worked at a gold mine when he was young.
People in this village have long made their living by digging the gold mine.
金山 (きんざん) means a gold mine, while 金山 (かなやま) refers more generally to a metal mine or is used as a place name, the two being distinguished only by reading.
Compound of 金 (きん, 'gold') and 山 (ざん, 'mountain' or 'mine'). The reading ざん is a voiced variant of さん used in compounds.