I have a couple of these stones, one male and one female, as ridiculous as that may sound...it boggles my mind that someone can have a registered trademark for an element of Nature.
Boji® stones are concretions composed of either iron sulfide, i.e pyrite and marcasite, or in some cases jarosite, which are found in outcrops of the Smoky Hill Chalk Member of the Niobrara Formation within Gove County, Kansas. They are typically associated with thin layers of altered volcanic ash, called bentonite, which occur within the chalk comprising the Smoky Hill Chalk Member. A few of these concretions enclose, at least in part, large flattened valves of inoceramid bivalves. The "female" Boji® stones are smooth concretions, which range in size from a few millimeters to as much as 12 mm (6 inches) in length. Most of these concretions are oblate spheroids in shape. The "male" Boji® stones are small polycuboidal pyrite concretions, which are as much as 7 cm (0.23 foot ) in diameter (Hattin 1982). These concretions will explode if thrown in a fire. Also, when they are either cut or hammered, they produce sparks and a burning sulfur smell.