These tourmaline, variety schorl, crystal twins are from Erongo Mt. in the Erongo Region of Namibia. This area contains 60 different mineral species including tourmaline. Schorl is an iron rich variety of tourmaline that contains the elements Na, Fe, Al, Si, O, B, and H. This is a pair of interpenetrating vee-twin crystals. The crystals are black with complex and multiple terminations. They have an adamantine luster. The piece measures 3 1/2 tip to tip at the top of the vee, x 2 x 1 1/4 inches or 90 x 50 x 32 mm.