Gaudefroyite is an extremely rare Manganese Borate and is especially difficult to find in crystal form from any locality. This specimen features several sharp, lustrous, prismatic black crystals of Gaudefroyite with Hematite. The crystals of Gaudefroyite on this specimen measure up to 1.1 cm, which is especially good size for the species. A great large thumbnail specimen of a very rare species. 3.0 x 1.9 x 1.9 cm