Labradorite: A Feldspar with a Distinctive Optical Characteristic

Labradorite belongs to a large group of silicate minerals, believed to make up more than half of the Earth’s crust, known by the name of feldspar. Labradorites are usually found in the igneous rock formations all around the world. Before discussing the wonderful optical characteristics associated with this stone, let’s delve into some of the details about its geographical occurrence.

Presence of Labradorite in the Nature

Labradorite can be found in different unique geographical settings. They are mostly formed through the process of metamorphism in which igneous rock of norite and basalt transforms into foliated rock formations. But they can also be found in sedimentary rock specimens that break away from the geological formations containing labradorites due to extreme environmental conditions.

Labradorescence:  Exhibition of Schiller Effect From This Feldspar Specimen

Some of the labradorite specimens have the inherent ability to exhibit rare optical phenomenon of adularescence which is commonly known as Schiller effect. In this optical exhibition, stones glow with a sheen which is coming from the inside of the stone instead of its surface. Opal, agate and moonstone are the widely known gemstone or ornamental specimens which possess the property of adularescence.

However, this same phenomenon becomes very different altogether, and in a good sense, when it is observed in some of the labradorite stones. Because few specimens are so good with the Schiller effect that they simultaneously exhibit multiple colors from the inner layers of their structure. Due to this distinctive and strong demonstration of adularescence, this phenomenon has got its own name as “labradorescence”.

How Labradorescence occur?

We have already known that how adularescence works. Labradorescence also plays in the same way where light reflects back from the internal surfaces instead of the exterior of the stone but here more than one type of wavelengths are reflected back by the internal twinning layers of the stone which are seen in the form of different colors ( blue, orange, red, green) by the observers. Labradorites possess adularescence or labradorescence are considered gem-grade feldspar.

Famous Labradorite Mining Locations

There are geographical locations all around the world which are famous for the deposits of labradorite.

Labrador, Canada: Birthplace of Labradorite

These unique feldspar stones were discovered in the 17th century on the Isle of Paul, Labrador, Canada and hence named after the place which is a province of present day Canada.

Gray and Black Labradorite: Russia and Madagascar

Gray and black labradorites which exhibit fine labradorescence can be found in Russia and Madagascar. It is interesting to note that both of the countries are more than 6000 miles apart but still host the same variants of labradorites.

Spectacular Deposits in Finland

Labradorites with an exceptional exhibition of labradorescence are mined from rare deposits of feldspar in Finland. They even named by the local administration “spectrolite” because of their spectacular display of rare optical characteristics.  

Oregon Sunstone: A National Labradorite Deposit

Labradorites are also mined in the US. However, they don’t possess the characteristics of labradorescence. Feldspar mines in the state of Oregon produces these stones different hues with a more transparent crystalline structure.

Labradorites mined in these sites are branded with the name of ‘Oregon sunstone’ and there is a reason to that. Many of the stone specimens found in this area contain metallic inclusions in the form of copper impurities. Due to this, these labradorites get the property of flashing with aventurescence in the presence of light. This specific property of Oregon labradorites compensates the absence of labradorescence. It is in great demand due to its popularity among local jewelry dealers and tourists.   

Labradorite: As a Gemstone and Décor Material

Labradorites with strong exhibition of Schiller effect are usually cut into gem-grade sizes of stones. They have a Mohs Hardness of around 6, making them more suitable for jewelry items that are less exposed to abrasion. To cherish the labradorescence of the stones, they are cut into cabochons. These cabochons are cut in a way where their base is corresponding to the inner twinning layers producing adularescence flashes.

Some large specimens of the stone can be cut into slabs which then can be employed in the making of small sculptures and other decor articles.

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