Spectrolite is a rare variety of labradorite feldspar which exhibits intense labradorescence, schiller or iridescence.[1][2] The variety is a trade name for material mined in Finland.[1] Labradorite with the spectrolite play of colors has also reported from Madagascar.[3] It is noted for the play of colors from blue to red. It is often cut as a lapidary cabochon and used as a gemstone.
Finnish geologist Aarne Laitakari (1890—1975) had described the peculiar stone and sought its origin for years when his son Pekka discovered the deposit at Ylämaa in south-eastern Finland while building the Salpa Line fortifications there in 1940. Although labradorite is found in Labrador, Norway, Madagascar and Russia in addition to Finland, the Finnish stone exhibits a uniquely vivid iridescence. The name spectrolite was given to it by the elder Laitakari; it is a commercial name and is properly used only of gemstone-quality material from the Ylämaa deposit.
The quarrying of spectrolite began after the Second World War and has become a significant local industry. In 1973 the first workshop in Ylämaa became cutting and polishing spectrolite for jewels.