Iceland Spar is crystallized carbonate, a clear form of calcite. This mineral is double refractive as objects appear in two places when looking through the lens of an Iceland Spar. Vikings used Iceland Spar to assist them in finding the sun. In fact, they called it "Sunstone." Iceland Spar is also said to have helped in the understanding of light as waves and studied by the likes of Isaac Newton and Christiaan Huygens. If you need more light in your life, the Iceland Spar might be a good piece to consider. This powerful prism may just unlock the joyous rays you never knew existed!