Yup - definitely pyrite. Both the color and the crystal forms give it away. Gold is really quite yellow in comparison - find a piece of good gold jewelry and put it next to the pyrite in your samples, and you'll see what I mean.

But, interestingly enough, Colorado pyrite from several districts is what's called "auriferous pyrite", meaning that it contains gold as an "impurity". In some locations, it's got enough gold in it to be mined as an ore of gold. But the gold still occurs in trace amounts.