Moonstone is a

sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...

potassium Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...

aluminium Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

silicate A silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is also used ...

((Na,K)AlSi₃O₈) of the

feldspar Feldspar ( ; sometimes spelled felspar) is a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagiocl ...

group that displays a

pearl A pearl is a hard, glistening object produced within the soft tissue (specifically the mantle (mollusc), mantle) of a living Exoskeleton, shelled mollusk or another animal, such as fossil conulariids. Just like the shell of a mollusk, a pear ...

y and

opalescent Opalescence or play of color is an optical phenomena, optical phenomenon associated with the mineraloid gemstone opal,opalescent. 2019. In Noah Webster's 1828 American Dictionary of the English Language. Retrieved January 7, 2019, from https:// ...

schiller. An alternative name for moonstone is hecatolite (from goddess

Hecate Hecate ( ; ) is a goddess in ancient Greek religion and mythology, most often shown holding a pair of torches, a key, or snakes, or accompanied by dogs, and in later periods depicted as three-formed or triple-bodied. She is variously associat ...

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 Diffraction is the deviation of waves from straight-line propagation without any change in their energy due to an obstacle or through an aperture. The diffracting object or aperture effectively becomes a secondary source of the Wave propagation ...

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 A solid solution, a term popularly used for metals, is a homogeneous mixture of two compounds in solid state and having a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The word "solution" ...

layers (lamellae) of different alkali

s (orthoclase and sodium-rich plagioclase). Polished moonstones often display

chatoyancy In gemology, chatoyancy ( ), also called chatoyance or the cat's eye effect, is an optical phenomenon, optical reflectance effect seen in certain gemstones. (Historically, the term has applied specifically to gems; in woods and other materials ...

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

Geology

The most common moonstone is of the

orthoclase Orthoclase, or orthoclase feldspar ( endmember formula K Al Si3 O8), is an important tectosilicate mineral which forms igneous rock. The name is from the Ancient Greek for "straight fracture", because its two cleavage planes are at right angles ...

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

adularia Orthoclase, or orthoclase feldspar (endmember formula potassium, Kaluminium, Alsilicon, Si3oxygen, O8), is an important Silicate minerals#Tectosilicates, tectosilicate mineral which forms igneous rock. The name is from the Ancient Greek for "stra ...

, named for an early mining site near Mt. Adular in

Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...

, now the town of St. Gotthard.Moonstone Gemological Information
International Gem Society, Retrieved 01-05-15 A solid solution of the

plagioclase Plagioclase ( ) is a series of Silicate minerals#Tectosilicates, tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continu ...

oligoclase Oligoclase is a rock-forming mineral belonging to the plagioclase feldspars. In chemical composition and in its crystallographic and physical characters it is intermediate between albite ( Na Al Si3 O8) and anorthite ( CaAl2Si2O8). The albite:ano ...

+/− the potassium feldspar orthoclase also produces moonstone

specimen Specimen may refer to: Science and technology * Sample (material), a limited quantity of something which is intended to be similar to and represent a larger amount * Biological specimen or biospecimen, an organic specimen held by a biorepository f ...

s. Deposits of moonstone occur in

Armenia Armenia, officially the Republic of Armenia, is a landlocked country in the Armenian Highlands of West Asia. It is a part of the Caucasus region and is bordered by Turkey to the west, Georgia (country), Georgia to the north and Azerbaijan to ...

(mainly from

Lake Sevan Lake Sevan () is the largest body of water in both Armenia and the Caucasus region. It is one of the largest freshwater Alpine lake, high-altitude (alpine) lakes in Eurasia. The lake is situated in Gegharkunik Province, at an altitude of abov ...

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

, the

Austrian Alps The Central Eastern Alps (), also referred to as Austrian Central Alps () or just Central Alps, comprise the Main chain of the Alps, main chain of the Eastern Alps in Austria and the adjacent regions of Switzerland, Liechtenstein, Italy and Slov ...

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

Myanmar Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and has ...

Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

Sri Lanka Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka, also known historically as Ceylon, is an island country in South Asia. It lies in the Indian Ocean, southwest of the Bay of Bengal, separated from the Indian subcontinent, ...

, and the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

."Moonstone"
Encyclopædia Britannica, 2011. Web. 20 Jan. 2011. Historically, the most valuable, transparent moonstones with strong blue sheen came from Myanmar. Today, most commercial moonstones come from Sri Lanka.

Varieties

Moonstone is a type of feldspar that comes in several varieties. All moonstone varieties show adularescence, which creates a soft, flowing sheen that moves across the stone's surface. This effect results from light interference caused by alternating internal layers of albite and orthoclase feldspar."Moonstone"
America's Collectibles Network. Retrieved 5 May 2025. Gemologists classify moonstone into several distinct varieties. Blue moonstone represents the finest variety of labradorite moonstone, with high transparency and strong blue adularescence. Blue moonstone can be found in Myanmar (formerly Burma), India, Madagascar, Malawi, Sri Lanka, and Tanzania. Labradorite moonstone belongs to the plagioclase feldspar group and forms within the triclinic crystal system, appearing in colorless, white, slight orange, or green varieties with a blue sheen. Orthoclase moonstone belongs to the monoclinic crystal system and displays a mystical white glow in colorless to white, orange, yellow, or brown hues. Gem enthusiasts often refer to adularescent labradorite with a multi-colored glow as "rainbow moonstone," which is colorless and highly transparent. Adularia, named after the Adular Mountains of Switzerland, forms in hydrothermal veins in mountainous regions as colorless to white, cream, pale yellow to pink, or reddish-brown, glassy, prismatic, twinned crystals that frequently display a white to blue sheen.

In culture

Moonstone has been used in

jewellery Jewellery (or jewelry in American English) consists of decorative items worn for personal adornment such as brooches, ring (jewellery), rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the ...

for millennia, including ancient civilizations. The Romans admired moonstone, as they believed it was derived from solidified rays of the Moon."Moonstone"
American Gem Trade Association. Retrieved 21 January 2011. Both the Romans and

Greeks Greeks or Hellenes (; , ) are an ethnic group and nation native to Greece, Greek Cypriots, Cyprus, Greeks in Albania, southern Albania, Greeks in Turkey#History, Anatolia, parts of Greeks in Italy, Italy and Egyptian Greeks, Egypt, and to a l ...

associated moonstone with their lunar deities. In more recent history, moonstone became popular during the

Art Nouveau Art Nouveau ( ; ; ), Jugendstil and Sezessionstil in German, is an international style of art, architecture, and applied art, especially the decorative arts. It was often inspired by natural forms such as the sinuous curves of plants and ...

period; French goldsmith

René Lalique René Jules Lalique (; 6 April 1860 – 1 May 1945) was a French jeweller, medallist, and glass designer known for his creations of glass art, perfume bottles, vases, jewellery, chandeliers, clocks, and automobile hood ornaments. Life Lalique ...

and many others created a large quantity of jewellery using this stone."Moonstone"
International Colored Gemstone Association. Retrieved 26 April 2012. The moonstone is the

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

State Gemstone; it was designated as such in 1970 to commemorate the

Moon landing A Moon landing or lunar landing is the arrival of a spacecraft on the surface of the Moon, including both crewed and robotic missions. The first human-made object to touch the Moon was Luna 2 in 1959. In 1969 Apollo 11 was the first cr ...

s, which took off from

Kennedy Space Center The John F. Kennedy Space Center (KSC, originally known as the NASA Launch Operations Center), located on Merritt Island, Florida, is one of the NASA, National Aeronautics and Space Administration's (NASA) ten NASA facilities#List of field c ...

. However, it does not naturally occur in the state. In

Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...

, moonstone is known as ''Mukdahan'', the same name as the northeastern province next to the river

Mekong The Mekong or Mekong River ( , ) is a transboundary river in East Asia and Southeast Asia. It is the world's twelfth-longest river and the third-longest in Asia with an estimated length of and a drainage area of , discharging of wat ...

, 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.

References

External links