Au and Gold dust

Au noun - A unit of length used for distances within the solar system; equal to the mean distance between the Earth and the Sun (approximately 93 million miles or 150 million kilometers).

Gold dust and au are semantically related. In some cases you can replace phrase "Gold dust" with "Au", this terms are similar.

Gold dust noun - The particles and flakes (and sometimes small nuggets) of gold obtained in placer mining.

Au and gold dust are semantically related. You can use "Au" instead a noun phrase "Gold dust".