All About Moonstone Adularescence

Photo by Amelia Isa, Flickr. CC license.   Adularescence sets moonstone apart from nearly every other gemstone on Earth. That shimmering, ethereal sheen that appears to ripple across the surface as though alive. This exquisite optical display has attracted attention throughout the ages, infusing moonstone with mystical powers. However, adularescence is a geological phenomenon which even in its physicality inspires wonder.  

What is Adularascence?

Adularescence occurs in gemstones when light interacts between alternating layers of mineral microstructures. Strictly an optical effect, it leads to interference and light scattering. (source) As a result, stones with adularescence appear to glow from the inside. This floating light appears to shift beneath the surface as you turn it gently in your hand. (source) This mystical light often billows across the stone's surface. Other times, it floats like wispy clouds drifting across the sky. While a number of gemstones demonstrate this exquisite optical effect, moonstone remains the most notable.   Moonstone Earrings by Amelia Isa, Flickr. CC license.  

Moonstone Adularescence

Moonstones belongs to the feldspar family of minerals. Feldspar minerals typically form in layers, as magma fills cavities and cools, then fills the cavities again. Moonstone consists of orthoclase and albite, in alternating layers. As light moves through the layers, encountering microscopic obstructions in the crystal structure, it bends and reflects back. Thus, appears to flow across the surface. According to the GIA, the finest moonstone appears colorless to the eye, nearly transparent, with an electric blue adularescence. The sheen should appear centered on the stone and remain visible from many different angles in the light. (source) Perhaps the most famous locality for moonstones is Mt. Adular in Switzerland. Not surprisingly, the word adularescence originates from this renowned source of these gorgeous gems. While moonstones are currently found all over the world, with Europe providing some of the most beautiful specimens, these gemstones actually date back to antiquity. Indeed, many legends abound regarding these fascinating stones.   Photo by Steve Adams on Unsplash.  

Moonstone Legends

Ancient Hindus believed the moon’s rays transformed into moonstone. The gem remains sacred in India, where the people believe it yields good fortune. Ancient Romans also associated it with the moon, believing it formed from drops of moonlight. Attributed to the goddess Diana, the gem bestowed love, wisdom, and prosperity on any who possessed her favored gemstone. These ancients also attributed clarity and foresight to the stone. Those who owned a moonstone made wise choices and saw well into the future, avoiding pitfalls along their path. (source)   Labradorescence. Photo by Prokofiev/Minerals, Wikimedia Commons.  

Other Stones that Adularesce

Opal displays a unique type adularescence called opalescence, with its play of vivid colors across the surface. Labradorite, found primarily in Labrador, Canada, displays a similar ethereal effect to moonstone. Experts call it labradorescence. Indeed, a special variety of labradorite originating in Madagascar displays a multicolored light show atop a pale stone. This singular variety goes by the trade name Rainbow Moonstone. Some varieties of quartz and agate, specifically rose quartz, also display adularescence to varying degrees. Oftentimes the effect is dampened by the presence of inclusions. However, well-cut cabochons can enhance the effect. Adularescence is just one of the magical, mystical properties that make gemstones so captivating. What is your favorite adularescent gemstone? ~Angela Magnotti Andrews