The Quarry mine in Stardew Valley is an area you can access after you complete the 'Bridge Repair' community center or Joja bundle. This is an area that consistently spawns stone, ore, and gems, no matter how often you clear it out. This area also has a cave where you can get your hands on the Golden Scythe. You can also have access to your own personal Quarry on your farm if you choose the 'Mountain Farm' option at the beginning of the game.