A world class specimen of this rare mineral! Big (up to 7 cm) Calcite crystals are the matrix for hundreds of sparkling, lustrous Jacobsite crystals. Jacobsite is rarely found much bigger than micro sized. The best come from the Kalahari and this has by far the best esthetics I have ever seen. Sharp, bright groups of silvery-black crystals are nicely scattered on the contrasting Calcite. The Calcite is in excellent condition and the dark Jacobsite can be clearly seen inside the crystals. Rare black minerals are reputed to be ugly, this is not!