Fortune

Fortune is an enchantment applied to mining and digging tools that increases the amount and/or chances of specific item drops. It does not increase experience drops.

Usage
For coal, diamond, emerald, nether quartz, and lapis lazuli, Fortune I gives a 33% chance to multiply drops by 2 (averaging 33% increase), Fortune II gives a chance to multiply drops by 2 or 3 (25% chance each, averaging 75% increase), and Fortune III gives a chance to multiply drops by 2, 3, or 4 (20% chance each, averaging 120% increase). 1 drop has a weight of 2, and each number of extra drops has a weight of 1. For the above types of ore, the formula to calculate the average drops multiplier with Fortune of level x is 1/(x+2) + (x+1)/2, which means Fortune IV gives 2.67x drops on average, Fortune V gives 3.14x drops on average, etc.

For redstone, carrots, glowstone, sea lanterns, melons, nether wart, potatoes, sweet berries, beetroots (seeds only) and wheat (seeds only), each level increases the drop maximum by +1 (maximum 4 for glowstone, 5 for sea lanterns, and 9 for melon slices).

For tall grass, each level increases the drop maximum by +2.

Fortune increases the probability of flint dropping from gravel, and saplings and sticks dropping from leaves, and apples dropping from oak and dark oak leaves. These rates are hardcoded, and using higher levels of Fortune unobtainable in survival mode will cause the blocks to use the rates for Fortune III.

Weeping vines and twisting vines use a unique Fortune calculation.

Incompatibilities
Silk Touch and Fortune are mutually exclusive. If commands are used to apply both Silk Touch and Fortune to an item, the Silk Touch enchantment takes precedence over the Fortune enchantment for blocks affected by both enchantments.

History
Enchantement 幸運 (エンチャント) Fortuna 时运