Iceland spar is a transparent variety of calcite, or crystallized calcium carbonate, originally brought from Iceland, and used in demonstrating the polarization of light. A ray of unpolarized light passing through the crystal divides into two rays of perpendicular polarization directed at different angles, called double refraction. So objects seen through the crystal appear doubled.
NOTE: The item photographed is similar to the one you will receive. These specimens are approximately 1.5" in length, and weigh approximately 2 ounces each. Country of Origin: Brazil.