Ferberite with Quartz. Quartz Ferberite is the iron endmember of the manganese - iron wolframite solid solution series. The manganese endmember is hübnerite. Ferberite is a black monoclinic mineral composed of iron.
Cave of the Crystals or Giant Crystal Cave is a cave connected to the Naica Mine 300 metres below the surface in Naica, Chihuahua, Mexico. The main chamber contains giant selenite crystals, some of the largest natural crystals ever found.