Vikings: early physicists?

[xasholex]

A Sunstone was used as an early compass? It works by refracting the suns rays, when the ray enters the crystal, it refracts into two rays. The rays are of equal intensity when the crystal is in the direction of the same polarization? which means it's in the direction of the sun.

I think I heard that right. Excuse any random typo-ness in facts. That's really neat though.