93 • FLINT GENUS. \ i Ufe. It is ufed for cutting and polifhing hard bodies; it is even employed for cutting fapphire and oriental ruby. Ohfervations. 1. Its high degree of hardnefs, and affinity to co rundum, have induced me to give it its prefent place in the fyftem. s 2. May not this, and the four preceding fpecie 3 * be arranged in the following order ? Ruby Family. Spinelle. Sapphire. a. Sapphire. b. Oriental ruby. Corundum. a. Common corundum. b. Diamond fpar. c. Emery, or compact corundum. 3. Magnetic iron flone, and iron glance, from the 11 ” being employed in place of emery in polilhing haf^ bodies, have been confounded with it. 61 SIXTEENTH