Calcite is one of the simplest examples of double refraction. By using a hand sample of calcite, we will explore this topic of double refraction. Double refraction occurs when a ray of light enters the crystal and due to calcite's unique optical properties, the ray is split into fast and slow beams. As these two beams exit the crystal, they are bent into two different angles (known as angles of refraction) because the angle is affected by the speed of the beams. A person viewing into the crystal will see two images of everything. The best way to view the double refraction is by placing the crystal on a straight line or printed word (the result will be two lines or two words). Looking at this 3D model how many rays of light do you see