See my post 33 below.
The You tube series actually visits a place on the Oxus river where the sand contains gold particles. The people build wooden placer mining troughs very similar to those used in California and the Yukon onto which they pour the sand slurry. The final stage is a sheep skin. The wool catches the fine gold and it is quite visible and easily removeable.
They have been at it for thousands of years.
Thanks.
This was the true golden fleece in the story of Jason (the Argonauts, and Medea), the sheepskin used to catch the flecks of gold.