Anomalously high fracture toughness of polycrystalline optical fluorite from the Suran deposit (south urals)

Mechanical characteristics, cathodoluminescence properties, and structural features of polycrystalline samples of optical fluorite from the Suran deposits were studied. The ceramic samples were cut by the diamond saw, and were ground and mechanically polished. The strain was induced at room temperature by the diamond Vickers pyramid. The SEM studies of the cathodoluminescence in the Suran fluorite samples demonstrated that the intensity of luminescence for some crystallites was higher by 20-30% than for CaF2 crystals.