Interesting Stuff Thread

scientists using an experimental setup with a similar crystal with the one found in a shipwreck have shown that such stones could indeed have helped the Vikings navigate from Norway to North America.

“The Vikings could have discovered this, simply by choosing a transparent crystal and looking through it through a small hole in a screen,” study researcher Guy Ropars said. “The understanding of the complete mechanism and the knowledge of the polarization of light is not necessary.”

It’s believed the Vikings used a common calcite crystal, called Icelandic spar. This stone has the special property that allows light to get polarized and broken into two – “ordinary” and “extraordinary” beams – when sunlight enters the crystal. Vikings might have calibrated calcite crystal sunstones by scanning them across a clear sky and noting the sun’s position when the crystal brightened. They could then repeat the trick to locate the sun when it was no longer visible by guiding themselves after the same reference point, subsequently marked.