Mysterious Viking Sunstones

The Vikings, seafaring warriors from Scandinavia, are believed to have navigated their ships with remarkable precision across the North Atlantic during the medieval period (about 500-1500 C.E.). [A] One key to their navigational success may have been the use of so-called “sunstones,” as described in Icelandic sagas (medieval Icelandic texts). Some argue the sagas’ content is mythical, while others suggest these stones were real tools used by the Vikings, probably crystals, such as Iceland spar. Iceland spar is a transparent variety of calcite that possesses unique optical properties. [B] It polarizes light by splitting light into two beams, creating a double image when the stone is held up to the sky. By rotating the crystal, the Vikings could determine the location of the sun in the sky on cloudy days, which would help them maintain their course. [C] However, evidence of actual sunstone use remains scarce. Archaeologists have yet to uncover these stones in the remains of Viking settlements or ships. But an Iceland spar sunstone was recovered from a ship that sank in 1592, suggesting that this navigational tool was indeed used for quite some time. [D] The theoretical use of sunstones remains a fascinating example of Viking [#highlight4]ingenuity[/highlight4].