Efficiency V first, always
Efficiency V is the no-brainer: mining speed skyrockets, and with haste II from a beacon you break stone near-instantly. It is also the cheapest max-level enchant to buy from a librarian. Every pickaxe — mining, farming, caving — takes Efficiency first.
The fork: Fortune or Silk Touch
Fortune III multiplies drops on coal, diamond, emerald, redstone, lapis and nether quartz — the mining-for-profit pickaxe. Silk Touch collects the block itself: ore blocks for later (mine now, Fortune later after a beacon), glass without breaking, budding amethyst... (never — see the geode guide), ender chests and bee nests. The standard play: own both — a Fortune pick for resource runs and a Silk Touch for specialty collection.
Unbreaking and Mending close the set
Unbreaking III + Mending makes any pickaxe immortal, and both pair with either fork. A Fortune III + Efficiency V + Unbreaking III + Mending pickaxe is the single most valuable tool in survival — the librarian reroll grind is worth it for this one item alone.
