searching for gold; gold hunting
Refers to the act of looking for gold, whether as a hobby, prospecting, or in a treasure-hunting context.
川で金探しをするのが彼の趣味だ。
His hobby is searching for gold in rivers.
Compound of 金 (きん, 'gold') and 探し (さがし, 'searching'), the noun form of 探す (さがす, 'to search').