Labradorite: Meaning, Properties, Uses

Labradorite is a feldspar mineral that is known for its iridescent sheen, which is caused by the interference of light waves within the mineral. This phenomenon, known as labradorescence, can produce a wide range of colors, including blue, green, yellow, and orange.

Labradorite, a mesmerizing feldspar mineral, is renowned for its enchanting iridescence, often resembling the captivating dance of the Northern Lights. Its captivating beauty and profound symbolism have captivated cultures worldwide, earning it a place among the most revered gemstones.

Labradorite, named after its discovery in Labrador, Canada, is a member of the plagioclase feldspar group, the most abundant group of minerals on Earth.

Labradorite samples

Labradorite Formation

Labradorite is a feldspar mineral that occurs in various igneous, metamorphic, and sedimentary rocks. It is most commonly found in mafic igneous rocks such as basalt, gabbro, and norite. The most common mode of labradorite formation occurs within igneous rocks, which are formed from the cooling and crystallization of molten magma or lava. As magma cools slowly underground, the various minerals within it begin to solidify, each with its own unique crystallization temperature. Labradorite typically crystallizes at intermediate temperatures, after olivine and pyroxenes but before amphiboles and feldspars like orthoclase.

Labradorite can also form through metamorphic processes, where existing rocks are transformed under high pressure and temperature conditions without melting. This often occurs in deep burial environments or along tectonic plate boundaries. During metamorphism, the mineralogy of existing rocks can change due to the breakdown of some minerals and the formation of new ones. Labradorite can form from the alteration of other plagioclase feldspars or from the interaction of other minerals with silica-rich fluids.

The labradorescence of Labradorite
Photo: Martin Heigan

Labradorescence

Labradorescence, the mesmerizing play of colors seen in labradorite, is a result of light interference and scattering within the mineral's intricate structure. This optical phenomenon occurs when light encounters microscopic lamellae, alternating layers of different feldspar minerals, embedded within the labradorite. As light interacts with these lamellae, its path is altered, causing the different wavelengths of light to reflect and scatter at varying angles. This interplay of light waves gives rise to the captivating iridescence that characterizes labradorescence.

The intensity and color palette of labradorescence depend on several factors, including the size and spacing of the lamellae, the composition of the minerals involved, and the angle at which light strikes the stone. The lamellae, typically less than a micron in thickness, act as miniature diffraction gratings, causing different wavelengths of light to interfere and reinforce each other. This interference produces the iridescent hues that dance across the labradorite's surface, shifting and shimmering as the stone is moved.

The colors of labradorescence can range from subtle blues and greens to vibrant yellows and oranges, sometimes even exhibiting a fiery red glow.

Natural Labradorite.
Photo: Andrew Moulder-Bruce

Labradorite Properties

Labradorite is a fascinating mineral with a variety of physical properties that contribute to its unique beauty and significance. Here's a comprehensive overview of its physical characteristics:

Chemical Composition: Labradorite belongs to the plagioclase feldspar group, with a chemical formula of (Na,Ca)₁₋₂Si₃₋₂ O₈. It primarily consists of sodium, calcium, and aluminum silicates. The ratio of sodium to calcium varies, determining the labradorite's composition within the plagioclase series.g

Crystal Structure: Labradorite crystallizes in the triclinic crystal system, the most complex crystal system. This means that its unit cell has unequal sides and angles, giving rise to its distinctive optical properties.

Mohs Hardness: Labradorite exhibits a Mohs hardness of 6 to 6.5, indicating its ability to resist scratching and abrasion. This hardness makes it suitable for jewelry and other decorative applications.

Cleavage and Fracture: Labradorite has two prominent cleavage planes that intersect at an angle of about 86 degrees or 94 degrees. These cleavage planes provide a preferential direction for the mineral to break along. Labradorite also exhibits an uneven to conchoidal fracture when broken across the cleavage planes.

Luster: Labradorite typically exhibits a vitreous to pearly luster, meaning it has a glassy or waxy shine. The iridescence of labradorescence, however, can create a metallic or greasy luster in some specimens.

Color: In reflected light, labradorite is usually clear, white, or gray. However, it is renowned for its labradorescence, a dazzling play of colors that can range from blue, green, and yellow to orange and red. The color of labradorescence depends on the size, spacing, and composition of the microscopic lamellae within the mineral.

Transparency: Labradorite can be translucent to transparent, meaning light can pass through it to varying degrees. The transparency is affected by the presence of inclusions and the intensity of labradorescence.

Density: Labradorite has a specific gravity of 2.68 to 2.72, indicating its relatively high density compared to other minerals. This density is attributed to its tightly packed atomic structure.

Streak: The streak of labradorite is white, meaning the color of the powder it produces when scratched is white. This streak is a helpful diagnostic tool for identifying minerals.

Fluorescence: Labradorite typically exhibits inert to weak fluorescence under long-wave ultraviolet (LW) light. This means it does not glow brightly under UV light.

Inclusions: Labradorite can contain various inclusions, such as black-needle-like inclusions, metallic-like platelets, and repeated twinning. These inclusions can affect the mineral's appearance and transparency.

Rough labradorite in Anorthosite rock. Anorthosite is a coarsely-crystalline, intrusive igneous rock dominated by plagioclase feldspar. from Ylämaa village, southern Kymi Province, southern Finland
Photo: James St. John

Labradorite Types and varieties

Spectrolite: Spectrolite, also known as Finnish labradorite, is the most prized variety of labradorite, distinguished by its exceptional iridescence and vivid colors. It showcases a dazzling display of blue, green, yellow, orange, and red hues, reminiscent of the Northern Lights.

Oregon Sunstone: Oregon sunstone, primarily found in Oregon, USA, is characterized by its aventurescence, a shimmering effect caused by inclusions of copper platelets. It typically displays golden, orange, and red hues, resembling the warmth of the sun.

Rainbow Moonstone: Rainbow moonstone, also known as adularescence labradorite, exhibits a milky appearance with a soft, rainbow-like iridescence. It's often translucent or semi-transparent, allowing light to gently permeate the stone.

Grey Labradorite: Grey labradorite, the most common variety, displays a range of grey hues from light grey to dark grey. It may exhibit subtle labradorescence in shades of blue, green, or yellow.

Polished Labradorite

Occurrences of labradorite

Here are some of the notable occurrences of labradorite around the world:

Canada: Labradorite was first discovered on Paul Island in Labrador, Canada, which is why it is named after this region. Other notable occurrences in Canada include the Nain anorthosite body in Labrador and the Thunder Bay area of Ontario.

Madagascar: Madagascar is known for its high-quality labradorite, particularly from the regions of Madagascar and Vohilava. The labradorite from Madagascar is known for its intense blue and green labradorescence.

Norway: Norway has several occurrences of labradorite, including the Lofoten Islands and the Egersund area. The labradorite from Norway is known for its yellow and orange labradorescence.

United States: Labradorite is found in various parts of the United States, including New York, Oregon, and California. The labradorite from the United States is known for its variety of colors, including blue, green, yellow, and orange.

Finland: Finland has several occurrences of labradorite, including the Ylämaa area and the Lappeenranta area. The labradorite from Finland is known for its blue and green labradorescence.

Uses of Labradorite

Labradorite beauty and versatility have led to its use in various applications, ranging from jewelry and decorative objects to metaphysical and therapeutic practices.

Natural Labradorite Var. moonstone Raw Stone Necklace

Jewelry: Labradorite is a popular choice in the creation of jewelry. Its unique iridescence makes it especially attractive for cabochons, which are often used in rings, earrings, necklaces, and pendants. Jewelers appreciate labradorite for its versatility and ability to add a touch of mystique to designs.

Carvings and Sculptures: The distinctive play of colors in labradorite makes it a sought-after material for ornamental carvings and sculptures. Artists often leverage the stone's optical effects to create visually stunning pieces, adding an element of uniqueness to their creations.

Decorative Objects: Labradorite is used in the creation of various decorative objects, such as beads, vases, and figurines. Its iridescence can enhance the aesthetic appeal of interior decorations and artistic displays.

Metaphysical and Spiritual Practices: Labradorite is believed by some to possess metaphysical properties, including the ability to enhance intuition, provide protection, and promote self-discovery. It is often used in meditation and energy healing practices, with individuals attributing spiritual significance to the stone.

Art and Craft Projects: Labradorite can be incorporated into various art and craft projects due to its unique visual effects. Its use in mosaics, collages, and mixed-media artwork adds a touch of iridescence and sophistication.

Lapidary Work: Lapidarists and gem cutters utilize labradorite to create polished cabochons and faceted gems. The stone's hardness and play of colors make it an intriguing material for lapidary work, contributing to the creation of gemstone collections and bespoke jewelry.

labradorite from Madagascar

In summary, labradorite is a mineral appreciated for its striking play of colors, making it a valued gemstone in the world of jewelry and decorative arts. Its geological properties contribute to its allure and versatility in various applications.