Iceland Spar is a transparent crystal form of the mineral calcite, known for its unique optical properties. It can split light into two separate rays, a phenomenon called double refraction. This characteristic makes it valuable in various scientific applications, including optics and mineralogy. Discovered in Iceland, this mineral has been used for centuries in polarizing microscopes and other optical devices. Its clarity and ability to manipulate light have also made it a subject of interest in the study of crystals and their properties.