Dark matter detector. Technician Cristina Cozzini of the Gran Sasso Laboratory holding a sapphire crystal encased in copper. This is part of a detector used to look for Weakly Interacting Massive Particles (WIMPs), a type of dark matter. The crystal is coated with a thin film of tungsten superconductor. When a WIMP hits the sapphire a small amount of energy is released, which is revealed by the changing resistance of the tungsten film. The Gran Sasso Laboratories are in Abruzzo, Italy. The laboratories are located 1400 metres underground. The rock overlay shields the laboratories from cosmic rays.