Iceland spar is a clear variation of calcite, it exhibits the rhombic crystal system of calcite perfectly, the crystals easily divide into rhombs, making them well sought after for a variety of reasons. Originally reported from Helgustadir Mine, Eskifjord, Iceland, hence its name. One of the most remarkable aspect of Iceland spar is its refractive properties. When light passes through one of the crystals, it is divided into two rays at different angles which results in a double refraction effect. Essentially, anything seen though the crystal is seen in double. This can best be seen if you place the calcite over some text, it will appear as if it has been printed twice. These mineral samples come from Santa Eulalia, Chihuahua, Mexico and are available in 2 sizes, they will come supplied in a card tray with an information label.