OK… in hindsight I should probably have done this first, I took some flakes of gold that I have and compared the colour with the material in the sample photo is very slightly lighter / brassier… I crushed another piece of the rock sieved it through a piece of fly screen and panned it. no visible gold but lots of tiny silver grains, probably cant see them very well in the photo tho.
Before Panning
After Panning