The sixth installment of Thumbnail Thursday is a single cube of Pyrite from Duff Quarry in Huntsville, Ohio. Pyrite from this location is more common to be diploid or trapezohedral. Cubes are uncommon, but not unheard of.
A thumbnail sized specimen is generally regarded as one that's between 25mm and 35mm and can fit inside a standard sized, 1.25" Perky box. I sell a variety of perky box products here at perkyboxes.com. I also sell filtered UV flashlights here.