In 1940 in an area near the lake Ylijärvi in Ylämaa was found labradorite, where the hues of the rainbow are especially rich. It was later named to spectrolite. The play of colours is caused by interference of light waves, and the colours reflect hues from golden browns to darkest blues.

The spectrolite is regarded as the world's most beautiful labradorite.

More information about spectrolite http://www.ylamaa.fi/english/2.html