Too blue for quartz? Plus, I'd like to think that anyone involved with mining would recognize quartz, therefore I suppose Terrible-One asked the question because (to him at least) it's obviously something other than quartz. To put it another way, quartz is extremely common, and he posted because something looked different about this piece.
Maybe it's quartz, the photo doesn't prove it one way or the other, but I would not be so quick to dismiss it as quartz. I'm not so sure that the stuff others have said is pyrite is pyrite either, the photo ain't that good.
--Dave J.