Sunstone crystals are mentioned in many Icelandic sagas. Vikings, a fierce race of warriors who used to travel over the vast expanse of waters in the Longships were the ones who made use of this sunstone to guide them.

The Vikings navigated extremely challenging waters of the North Atlantic in open, hand-built wooden ships equipped with massive sails. One might wonder, how did the Vikings know where they were going?

Archaeologists have discovered a special crystal that suggests legendary Viking sunstone did exist in reality. The crystal was uncovered in the 1592 sunken Elizabeth shipwreck near the Channel Islands.

It is believed that Vikings used so-called sunstones as a compass to find their way in arctic waters. Researchers suggest that sunstone could have been held up toward the center of the sky, allowing sunlight to hit it and get polarized and broken into an ordinary beam.

On a clear day, they could have rotated the crystal until the pair of beams lined up. By noting where the sun when this happened, navigators could make a reference point to use when the sun was obscured by clouds.

This means that when the crystals are held up to the sky, the orientation of these patterns cast within the stone can help pinpoint the position of the sun below the horizon.

Once the Vikings had determined the position of the hidden sun, they could have used a specially designed wooden slab called a shadow stick to simulate the shadow of the gnomon based on the angle at which the hidden sun would hit it. The location of the outer edge of that imaginary shadow could then have been used to determine their cardinal direction.