Minecraft wiki entry for Amethyst_Shard, associated text: An amethyst cluster mined using a non-Silk Touch, non-Fortune pickaxe drops 4 amethyst shards. When mined using any other tool, item or mechanism (such as explosions or pistons) it drops 2 shards. The maximum amount of amethyst shards dropped can be increased with Fortune. Fortune I gives a 1⁄3 chance for eight shards, averaging 5.33 shards; Fortune II gives a 25% chance (each) to give eight or 12 shards, averaging 7 shards, and Fortune III gives a 20% chance (each) to give 8, 12, or 16 shards, averaging 8.9 shards.