I am going to say Pyrite! Note how the camera setting gave everything a yellowish/orange hue in the left and right pics thus giving the specimens a Gold look. However, the center pic appears to have been taken in natural light and (I believe) better shows the true color of the specimens.
HMM Always hard to tell from just a picture. If I had it in my hand I could tell you right away that its pyrite and Ill just go ahead and toss it for ya... Ya Im playin. It looks like gold to me but it is VERY polished looking. Most big gold isnt that shiny raw. Poster above has it right, Hit it with a hammer. If it smooshes/dents its gold and if it fractures its pyrite. Good luck!