Microcrystals of rich, yellow gold are concentrated on one side of the Precambrian hematite matrix on this rare specimen from a very uncommon locality in Uruguay (we obtained this from a friend who got these from an exploration geologist - I am sure of the validity of the source, just he won't divulge exact details yet). There are more microcrystals of gold scattered elsewhere. An unknown blue mineral is a fine accent. Unique in my experience.