For this week’s gemstone highlight, I thought we could continue along the mystical moon vein started last week by taking a look at the moonstone. All hallows’ eve is coming up soon, after all.
Geology | Origins of a Gemstone
Moonstone originates from the “potassium aluminosilicate” variety of the large mineral group of feldspars. With feldspar making up over half of the Earth’s crust composition, it’s likely that you could pick up a rock anywhere in the world, and it would probably contain at least one mineral from the feldspar group (University of Minnesota, Potassium Feldspar). In its rough form, potassium feldspars typically form pink, reddish or white, hard blocky crystal masses. The potassium feldspar series has its own sub-varieties, including: orthoclase, sanidine, oglioclase and microcline.
Moonstone is typically cut from the sanidine or orthoclase. Sanidine is a high temperature form of potassium feldspar and has a less ordered crystal structure than orthoclase. It is primarily found in volcanic igneous rocks where magmas cooled more rapidly and crystals have less time to form, resulting in a distinctive bluish iridescence (University of Minnesota). During formation, intermingling minerals, orthoclase (potassium feldspar) and albite (a plagioclase feldspar), separate into stacked, alternating layers (GIA, Moonstone). As incident light rays play between these thin layers, they scatter, producing the optical phenomenon called adularescence. The visual outcome of this light effect is a milky blue luster and the appearance of a floating light or sheen that seems to billow across the stone’s surface as it’s rotated. This effect has often been artfully compared to lunar light floating on water, and it is the inspiration for its given gem name. A quality cut when working with the crystal rough, will maximize this beautiful play of light.
Rainbow moonstone is typically derived from the labradorite (plagioclase feldspar series) species.
The Romanticism of the Moonstone
The moonstone gemstone has a rich cultural and mystical history that dates back long before it was designated as a June birthstone or popularized in western culture by Art Nouveau. Several ancient legends have suggested that moonstones were formed from moonbeams or drops of moonlight. According to some sources, moonstones in India were considered “’dream stones,’ that could bring the wearer beautiful visions at night”. In Arabic culture, moonstones were a symbol of fertility (gemstone.org, Moonstone).
The romanticism that speaks to me the most is the belief in the moonstone as a “lover’s stone”:
The moonstone symbolizes our being in its entirety. With its shimmer, it strengthens our emotional and subconscious aspects….a “lover’s stone”, [it] evokes tender feelings and [safeguards] the true joys of love. It is also said that wearing a moonstone strengthens our intuition and our capacity to understand. (gemstone.org, Moonstone)
Of course, many folks will say that things like flower meanings or a gemstone’s mystical properties should be taken with a grain of salt. The same could be said for the whole “something borrowed, something blue,” bridal wedding tradition. Regardless of whether you choose to put stock in romantic ideology, I think moonstones make a lovely gem to wear on special date or even a wedding day. I, myself, wore rainbow moonstone shoulder-duster earrings during my nuptials.
They are subtle and elegant, with glimmers of a joyful play of light. Plus, they will work regardless of whether you’ve opted for the traditional white/ off-white gown, or something of a blush variety. Moonstones also make a nice alternative to the pricier opal. Be mindful, however, that moonstones may be susceptible to scratching, as they are considered a somewhat “soft” stone and fall to a 6 on the Mohs hardness scale. So, handle your moonstone jewelry with care!
Department of Geology. University of Minnesota. “Potassium Feldspar: Feldspar Group of Silicate Minerals.” 15 October 2015 <https://www.esci.umn.edu/courses/1001/minerals/potassium_feldspar.shtml>
GIA. “Moonstone Description.” 15 October 2015 http://www.gia.edu/moonstone-description
International Colored Gemstone Association. “Moonstone.” 15 October 2015 http://www.gemstone.org/index.php?option=com_content&view=article&id=126:sapphire&catid=1:gem-by-gem&Itemid=14