Labradorite is a captivating mineral renowned for its striking visual characteristic known as labradorescence. This optical phenomenon creates an iridescent play of colors, causing vibrant flashes of blue, green, yellow, orange, and sometimes purple to shimmer across its surface when viewed from different angles. This unique effect makes labradorite highly sought after for its aesthetic appeal. As a member of the feldspar mineral family, its allure stems from this internal spectacle. This article explores its geographical origins and formation processes.
The Original Discovery and Primary Source
Labradorite is named after Labrador, Canada, where it was first officially documented. Moravian missionaries discovered the mineral in 1770 on Paul Island, near the town of Nain, along the coast of Labrador. While these missionaries were the first to formally identify and name the stone, local Inuit peoples were already familiar with it, utilizing it in various tools and ornamental items.
Inuit folklore holds a deep connection to labradorite, often associating its colorful flashes with the Aurora Borealis, or Northern Lights. One legend suggests an Inuit warrior freed most of the Northern Lights from rocks along the Labrador coast, but some remained, giving the stone its characteristic glow. This mythical association cemented the stone’s cultural significance in the region.
Global Occurrences of Labradorite
Beyond its original discovery site in Canada, significant deposits of labradorite are found across the globe. Finland is known for Spectrolite, a variety discovered around 1940 during World War II. Spectrolite exhibits an exceptionally vibrant and full spectrum of colors.
Other notable sources include Madagascar, which produces stones with a wide range of colors and often striking blue or green labradorescence. Russia, particularly in the Ural Mountains, is another source of high-quality labradorite. Deposits are also found in Norway, Australia, China, Poland, Slovakia, Ukraine, Mexico, and various parts of the United States, including Oregon.
How Labradorite Forms
Labradorite is a calcium-enriched feldspar mineral, part of the plagioclase series. It primarily forms in specific types of igneous rocks, which solidify from molten magma or lava. It is commonly found in mafic igneous rocks such as basalt, gabbro, and norite. Large intrusive igneous bodies composed almost entirely of labradorite, known as anorthosite, are also significant sources.
The unique optical effect of labradorescence arises from the mineral’s internal structure. As magma cools slowly underground, microscopic, thin, parallel layers (lamellae) develop within the crystal. These layers have slightly different compositions, typically varying in sodium and calcium content. When light enters the stone, it interacts with these internal layers, causing interference and diffraction, which results in the vibrant flashes of color. The specific composition and slow cooling process are essential for forming these lamellar structures.