William Phillips, Transactions of the Geological Society (1811)
“ The fracture of the crystals, particularly of the more translucent ones, is very smooth and inclines to conchoidal; but is frequently uneven, and inclining to shattery, in those of a darker hue. I have met with some octohedrons that admitted a fracture in the direction of their faces, but have not found any of a cubical form in which a division parallel to the circumscribing planes was practicable. The form of the primitive crystal, according to Haüy, is the regular octahedron (fig. 1.) ”
