Minecraft wiki entry for Fortune, associated text: Glowstone, melons, nether wart, redstone ore, sea lanterns, and sweet berries use a discrete uniform distribution, meaning each possible drop amount is equally likely to be dropped. Fortune increases the maximum number of drops by 1 per level. However, maximum drop limitations may apply: glowstone has a capacity of 4 glowstone dust, sea lanterns have a capacity of 5 prismarine crystals, and melons have a capacity of 9 melon slices. If a drop higher than these maximums is rolled, it is rounded down to the capacity.