'Ancient legends of Viking mariners using mysterious sunstones to reveal the position of the sun on a cloudy day may well be true, according to a new study. While experts have long argued that Vikings knew how to use blocks of light-fracturing crystal to locate the sun through dense clouds, archaeologists have never found solid proof.
Vikings, they argue, used transparent calcite crystal - also known as Iceland spar - to fix the true bearing of the Sun to within a single degree of accuracy.
The recent discovery of an Iceland spar aboard an Elizabethan ship sunk in 1592 - tested by the researchers - bolsters the theory that ancient mariners were aware of the crystal's potential as an aid to navigation.
Even in the era of the compass, crews might have kept such stone on hand as a backup, the study speculates. 'We have verified that even only one of the cannons excavated from the ship is able to perturb a magnetic compass orientation by 90 degrees,' the researchers wrote. 'So, to avoid navigation errors when the Sun is hidden, the use of an optical compass could be crucial even at this epoch, more than four centuries after the Viking time.'
