Minecraft wiki entry for Ore, associated text: It is not efficient to mine with Silk Touch and then smelt an ore block that normally drops multiple pieces of its resource, because smelting these ores yields less experience and only 1 piece of the resource. Nether gold ore is the only exception, as each ore block drops an average of 8.8 gold nuggets even when mined with Fortune III, which is less than a guaranteed gold ingot obtained from smelting the ore obtained using Silk Touch.