Siegenite is an uncommon cobalt, nickel sulfide and is an extremely rare mineral from Missouri's Viburnum Trend. Isolated, extremely sharp, isometric, steel-gray siegenite crystals are very aesthetically scattered on the matrix crust and are nicely accented by contrasting chalcopyrite microcrystals. The lustrous siegenite crystals reach 5 mm. This thumbnail is very high-grade, older material from the famous Buick Mine and is seldom available in this quality. Ex. Carl Davis Collection.