Calcite, the most common form of natural calcium carbonate (CaCO3), a widely distributed mineral known for the beautiful development and great variety of its crystals.
A wavefront is a surface over which an optical wave has a constant phase. For example, a wavefront could be the surface over which the wave has a maximum (the crest of a water wave, for example) or a minimum (the trough of the same wave) value. The shape of a wavefront is usually determined by the geometry of the source.
shock wave. 1. a region of abrupt change of pressure and density moving as a wave front at or above the velocity of sound, caused by an intense explosion or supersonic flow over a body. 2. shock waves from the recent collapse of one of the nation's largest banks. I awoke in mid-air, as the shock wave hurled me against the bedroom's far wall.