Arsenopyrite, native gold and tetradymite. Portugal
Arsenopyrite (white-yellow, right) is extensively altered to scorodite light grey, centre left). Native gold (golden-yellow, centre) is approximately 960 fine and is intergrown with tetradymite (white, centre bottom), which shows strong cleavage along (0001) and alteration to a low reflectance undetermined phase. Quartz (bottom centre) is dark grey and encloses a gold grain.
Polished block, plane polarized light, x 80, air