HARDNESS: 3 – 4
DENSITY: 1,2 – 1,3 g/cm3
SCRATCH: Dark brown
COLOR: Bright black
EXFOLIATION- FRACTURE: Concoidea
CRYSTALLIZATION: Orthorhombic system
LUMINESCENCE: Yellowish green
Black-Jet has a compact conformation, is soft to the touch, light and quite hard. In Asturias it is called Acebache or Azebache. The best jet in the world, along with Whithby, is in Asturias in the Jurassic Coast, between Gijón and Ribadasella, with a texture, an intense color and incomparable hardness. Recent studies carried out by a research team of the University of Oviedo, show that the Asturian black-jet comes from a family of Jurassic trees, extinct 65 million years ago.