The Tarheel Gem & Mineral Club of Raleigh, NC has regularly hosted field trips to various Martin Marietta quarries throughout North Carolina.  Today the club went to the American Stone Quarry at 1807 Hwy 54 West in Chapel Hill, NC. 
1/4 inch pyrite cubes were locked inside some of the rock here.  Without a good 5 pound sledge hammer I would not have been able to get specimens of the pyrite.  I had to break larger boulders down in order to get something small enough to take home.  One only needs to explore the walls closely to find the spots where the pyrite is located.  Once discovered you only needed to smash the broken boulders around that wall to obtain specimens.  
A good friend and rock hound Bob located a vein of quartz in the quarry wall where some pretty interesting crystals were found.  The vug he discovered contained what looked like mangled quartz crystals.  There were many striations throughout all of the crystals as if another mineral had once grown through them and then dissolved.  Although ugly looking, they had personality.
This was about an 8 inch long ugly looking honker that had grown between a crack in the quarry wall and contacted on both sides.

Trips to mines such as this one can be great fun.  Since working quarries are always exposing new areas as a result of blasting you never know what you might find the next time you go out there.  Persistence can be a rock hounds best attribute.