There is an old Viking legend which tells of a glowing stone that could identify the location of the sun on a cloudy day when it was held up to the sky. Now researchers are beginning to wonder if Iceland spar may be that stone.
One Icelandic saga describes how, during cloudy, snowy weather, King Olaf consulted Sigurd on the location of the Sun. To check Sigurd’s answer, Olaf “grabbed a sunstone, looked at the sky and saw from where the light came, from which he guessed the position of the invisible Sun”
Using the polarisation of the skylight, as many animals like bees do, the Vikings could have used to give them true bearings.
The Viking routes in the North Atlantic were often subject to dense fog and the stone could also be used to locate the sun on very cloudy days.
Story: The Telegraph | Photo: ALAMY