Here is an extremely large example of pyrite and muscovite from Leaders Heights Interstate Highway 83 roadcut from York County , Pennsylvania . I am pretty sure that this is the largest recorded crystal from this locality . You can see in the image that the crystal itself measures about 1 13/16" . The overall specimen is about 5 1/2 - 6" long . The bottom the specimen has been cut to make it  stand up as shown . Old Stock . Purchased in a collection .