Even though I go to both the Tucson and Denver mineral shows almost every year, I rarely see gaudefroyite crystals for sale. Gaudefroyite is a calcium manganese borate. It doesn't <i>sound</i> that exotic, but crystals of any size are quite rare. That said, this is not just a rare specimen: the red andradite garnets in between the black gaudefroyites make this a beautiful piece. A few points are missing, but the beautiful crystal at the top is perfect, and 8+ mm long. Overall measurements are 5.1 x 4.2 x 2.0 cm.