Moonstone in gemstone

Moonstone is a sodium potassium aluminium silicate ((Na,K)AlSi3O8) of the feldspar group that displays a pearly and opalescent schiller. An alternative name for moonstone is hecatolite (from goddess Hecate).

Moonstone

General

Category Tectosilicate minerals, feldspar group, alkali series, orthoclase variety

Formula (Na,K)AlSi3O8

Crystal system Monoclinic

Identification

Color Can be numerous colors, including blue, grey, white, pink, peach, green and brown, as well as colorless

Cleavage perfect

Fracture uneven to conchoidal

Mohs scale hardness 6.0

Luster Opalescent

Streak white

Specific gravity 2.54–2.66

Optical properties for orthoclase and sanidine, biaxial (–); for oligoclase, biaxial +/–

Refractive index 1.518–1.547

Birefringence 0.005–0.01

Dispersion 0.012

Etymology

The name moonstone derives from the stone's characteristic visual effect, called adularescence (or schiller), which produces a milky, bluish interior light. This effect is caused by light diffraction through alternating layers of orthoclase and albite within the stone. The diffracted light varies from white to blue, depending on the thinness of the albite layers. More technically, this micro-structure consists of regular exsolution layers (lamellae) of different alkali feldspars (orthoclase and sodium-rich plagioclase).

Polished moonstones often display chatoyancy ("cat's eye" effect), where a luminous streak appears through the stone. Asterism is rare and produces four-legged stars.

Characteristics

Moonstone is primarily characterized by its adularescence, a bluish-white shimmer that glides across the entire surface of the stone when moved. Moonstones from the traditional country of origin, Sri Lanka, are usually almost completely transparent to milky white and have a delicate bluish sheen. Stones from India, on the other hand, exhibit a more opaque base tone that tends toward orange. Cloud-like interplay of light and shadow can occur.

Geology

The most common moonstone is of the orthoclase feldspar mineral adularia, named for an early mining site near Mt. Adular in Switzerland, now the town of St. Gotthard. A solid solution of the plagioclase feldspar oligoclase +/− the potassium feldspar orthoclase also produces moonstone specimens.

Deposits of moonstone occur in Armenia (mainly from Lake Sevan), Australia, the Austrian Alps, Mexico, Madagascar, Myanmar, Norway, Poland, India, Sri Lanka, and the United States. Historically, the most valuable, transparent moonstones with strong blue sheen came from Myanmar. Today, most commercial moonstones come from Sri Lanka.

Use as a gemstone

Moonstone is used exclusively as a gemstone. It is usually cut into a cabochon, as this shape best showcases the luster created by its lamellar structure. A chatoyation (cat's eye) effect can be observed when exposed to sharply defined light. Due to its low hardness and perfect cleavage, moonstone is very sensitive to pressure.

Moonstone has been used in jewellery for millennia, including ancient civilizations. The Romans admired moonstone, as they believed it was derived from solidified rays of the Moon. Both the Romans and Greeks associated moonstone with their lunar deities. In more recent history, moonstone became popular during the Art Nouveau period; French goldsmith René Lalique and many others created a large quantity of jewellery using this stone.

In Thailand, moonstone is known as Mukdahan, the same name as the northeastern province next to the river Mekong, Mukdahan. The name of the province comes from a folklore that a magical gemstone looked like a pearl floating above the Mekong in the area where the province is now located.

In popular culture

Moonstone is the state gemstone of Florida. It was designated as such in 1970 to commemorate the lunar landings, which took off from the Kennedy Space Center. Although it is the state gemstone, it does not occur naturally in the state.

In The Elder Scrolls, it allows the forging of elven and glass armor.

In season 2 of the television series The Vampire Diaries, the moonstone is used to break the curse of the werewolves.

In the Choose Your Own Adventure books of the Lone Wolf and Golden Star series, the moonstone is such a powerful magical object that it cannot remain without serious consequences in the human world; the calendar there originates from the year of its creation.

The Moonstone is a comic strip of the adventures of Johan and Pirlouit by Peyo, published in 1956.

In season 3 of Alexandre Astier's Kaamelott series, the druid Merlin manages to find the moonstone, which allows him to transform goat meat into fresh water. This feat is met with skepticism by King Arthur and Léodagan.

In season 3 of Teen Wolf, the walls of the Beacon Hills bank are covered in hecatolite, dispelling the moon's effects on werewolves.

'In these records, he (Septimius Severus) finds the Moon, that is to say the Moonstone, that is to say Julia Domna ', (who will become his second wife). (Extract from chapter 1 of Heliogabalus or the Crowned Anarchist by Antonin Artaud.)

Esotericism

Esotericists assign the moonstone to the zodiac sign of Cancer or Pisces. It is also considered a symbolic stone for Venus (Richardson/Huett), Neptune (Richardson/Huett), or the Moon. In German-speaking countries, it represents the month of June.

As a healing stone, moonstone is said to relieve headaches and gynecological problems (menstrual problems) as well as generally strengthen the psyche. There is no scientific evidence for these alleged physical and psychological effects.

Manipulations and imitations

Genuine gemstone-quality moonstone is rare, so it is often offered commercially as an imitation of white labradorite. This is especially true for the term "rainbow moonstone." Other imitations are created using burnt amethyst, synthetic spinel, or glass.

The following trade names are in circulation as of 2017:

Blue moonstone and California moonstone are misleading names for chalcedony with a bluish glow

Albite moonstone, Canadian moonstone and peristerite are trade names for a variety of albite in which potassium feldspar segregation lamellae create a moonstone-like effect

Rainbow moonstone is a blue-iridescent white labradorite (feldspar family)

Black moonstone is an outdated name for labradorite

Albite moonstone

Sourced from Wikipedia