Sunstones?

I’ve been outlining a fantasy of sorts. Nothing I have the time to work on right now, but I’m happy with the story idea and it has been something simmering for a long while.

I came across this article looking for a way to navigate without a magnet or the invention of a sextant and clock.  Very interesting. I sure would love to try it out sometime.

British and French scientists have long argued that the find is a sunstone — a device that fractures the light, enabling seafarers to locate the Sun even when it is behind clouds or has dipped below the horizon.

Sunstones, according to a theory first aired 45 years ago, helped the great Norse mariners to navigate their way to Iceland and even perhaps as far as North America during the Viking heyday of 900-1200 AD, way before the magnetic compass was introduced in Europe in the 13th century.