Vikings Navigated With Translucent Crystals?

Icelandic spar may have revealed sun's position on cloudy days, study says.

Vikings may have navigated by looking through a type of crystal called Icelandic spar, a new study suggests.

In some Icelandic sagas—embellished stories of Viking life—sailors relied on so-called sunstones to locate the sun's position and steer their ships on cloudy days. (See Iceland photos submitted by readers like you.)

The stone would've worked by detecting a property of sunlight called polarization.

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