Sunstones might really have worked for Vikings

[Brad]

Mysterious sunstones in medieval Viking texts could really have worked | Ars Technica https://arstechnica.com/science/2018/04/mysterious-sunstones-in-medieval-viking-texts-could-really-have-worked/#p3

[gm66]

I saw a doc about that a while back, trying to find ...

.. can't find, i think it was a BBC doc but it was agreed they were useable.

[Rumbas]

Wow, no wonder we roamed far and wide