According to the passage, why does the panning process work in uncovering gold?

The panning process works for uncovering gold because gold is a heavy metal. This is explained in the third sentence of the passage\u2019s first paragraph. The passage does not state that gold is magnetic or that it does not dissolve in water; therefore, those two options can be eliminated. The passage states that the material around the gold is lighter than the gold, as gold is a heavy metal; therefore, the passage implies that gold does not float.