Citrine is a transparent, yellow variety of

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

. Its name is derived from the Latin word ''citrus'' (citron tree), by way of the French ''citrin'' or ''citron'' (lemon). Citrine is one of the most popular yellow gemstones. It is sometimes used as a modern, more affordable alternative to the traditional November

birthstone A birthstone is a gemstone that represents a person's birth period, usually the month or zodiac sign. Birthstones are often worn as jewelry or a pendant necklace. History of birthstones Western custom The first-century historian Josephus bel ...

topaz Topaz is a silicate mineral made of aluminium, aluminum and fluorine with the chemical formula aluminium, Alsilicon, Sioxygen, O(fluorine, F, hydroxide, OH). It is used as a gemstone in jewelry and other adornments. Common topaz in its natural ...

. Not every yellow quartz is considered citrine, and there is disagreement as to when the name "citrine" is appropriately used. However, quartz stained by iron inclusions or coatings is generally not considered citrine. Natural citrine is rare; most commercially available citrine is produced by heating

amethyst Amethyst is a Violet (color), violet variety of quartz. The name comes from the Koine Greek from - , "not" and (Ancient Greek) / (Modern Greek), "intoxicate", a reference to the belief that the stone protected its owner from Alcohol into ...

smoky quartz Smoky quartz is a brownish grey, translucent variety of quartz that ranges in clarity from almost complete transparency to an almost-opaque brownish-gray or black crystals. The color of smoky quartz is produced when natural radiation, emitted fro ...

. Natural citrine tends to have a pale yellow, often smoky color, while heat-treated amethyst is typically a deeper yellow, orange, red, or even brown ("burnt amethyst").

Color

File:Citrine 1 (Russie).jpg, Twinned natural citrine crystals from Russia File:Quartz-60953.jpg, Natural citrine crystal from Brazil File:Citrin cut.jpg, Cut natural citrine File:Tumble-polished citrine 2.jpg, Tumbled "citrine" (heat-treated amethyst) File:Citrine. Bahia, Brazil-8845.jpg, "Citrine" crystal (heat-treated amethyst) File:Geode Reference -11.jpg, "Citrine" geode (heat-treated amethyst) Natural citrine ranges in color from yellow to yellow-orange or yellow-green. The causes of its color are not well agreed upon. Evidence suggests the color of citrine is linked to the presence of aluminum-based color centers in its crystal structure, similar to those of

. Both smoky quartz and citrine are

dichroic In optics, a dichroic material is either one which causes visible light to be split up into distinct beams of different wavelengths (colours) (not to be confused with dispersion), or one in which light rays having different polarizations are ab ...

polarized light , or , is a property of transverse waves which specifies the geometrical orientation of the oscillations. In a transverse wave, the direction of the oscillation is perpendicular to the direction of motion of the wave. One example of a polarize ...

and will fade when heated sufficiently or exposed to

UV light Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of t ...

. They occur in the same geological environments and can frequently be found together in the same crystal as “smoky citrine.” Smoky quartz can also be converted to citrine by careful heat treatment. Alternatively, it has been suggested that the color of citrine may be due to trace amounts of iron; many sources claim

iron oxide An iron oxide is a chemical compound composed of iron and oxygen. Several iron oxides are recognized. Often they are non-stoichiometric. Ferric oxyhydroxides are a related class of compounds, perhaps the best known of which is rust. Iron ...

s as the source of citrine's color. However, synthetic crystals grown in iron-rich solutions have failed to replicate the color or dichroism of natural citrine. The UV-sensitivity of natural citrine further indicates that its color is not caused solely by trace elements. Most citrine on the market is heat-treated

. Amethyst loses its natural violet color when heated to above 200-300 °C and turns a color that resembles natural citrine, but is often more reddish or brownish. Unlike natural citrine, the color of heat-treated amethyst is known to come exclusively from trace amounts of iron oxides, specifically

hematite Hematite (), also spelled as haematite, is a common iron oxide compound with the formula, Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of . ...

and

goethite Goethite (, ) is a mineral of the diaspore group, consisting of iron(III) oxide-hydroxide, specifically the α- polymorph. It is found in soil and other low-temperature environments such as sediment. Goethite has been well known since ancient t ...

. This iron was present in the original amethyst and oxidized by the heating process. Heat-treated amethyst does not exhibit the dichroism of natural citrine. Amethyst with a certain iron content can be heated to produce "madeira citrine," which has a deep orange color and exhibits red flashes. Its name comes from ''madeira'', the Brazilian word for wood. Clear quartz can also be irradiated to produce "lemon quartz," which has a neon yellow to yellow-green color.

Differentiation

Clear quartz with natural iron inclusions or

limonite Limonite () is an iron ore consisting of a mixture of hydrated iron(III) oxide-hydroxides in varying composition. The generic formula is frequently written as , although this is not entirely accurate as the ratio of oxide to hydroxide can vary qu ...

staining may resemble citrine. However, these crystals will either have coloration only on the surface or in certain spots ( inclusions) within the crystal. Quartz that derives its color from coatings or inclusions is not citrine. Geode Reference -22

Like amethyst, heat-treated amethyst often exhibits color zoning, or uneven color distribution throughout the crystal. In geodes and clusters, the color is usually deepest near the tips. Unlike heat-treated amethyst, natural citrine typically exhibits even coloration throughout the crystal and never occurs in geodes or clusters. Yellow topaz II

It is nearly impossible to differentiate between cut citrine and yellow

visually, but they differ in hardness. All quartz varieties have a hardness of 7 on the

Mohs scale The Mohs scale ( ) of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by the Ger ...

, while topaz has a hardness of 8.

Origin

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

is the leading producer of citrine, with much of its production coming from the state of

Rio Grande do Sul Rio Grande do Sul (, ; ; "Great River of the South") is a Federative units of Brazil, state in the South Region, Brazil, southern region of Brazil. It is the Federative units of Brazil#List, fifth-most populous state and the List of Brazilian s ...

. Other notable sources include

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

, the

Democratic Republic of the Congo The Democratic Republic of the Congo (DRC), also known as the DR Congo, Congo-Kinshasa, or simply the Congo (the last ambiguously also referring to the neighbouring Republic of the Congo), is a country in Central Africa. By land area, it is t ...

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 ...

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 ...

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 ...

Namibia Namibia, officially the Republic of Namibia, is a country on the west coast of Southern Africa. Its borders include the Atlantic Ocean to the west, Angola and Zambia to the north, Botswana to the east and South Africa to the south; in the no ...

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

, 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 ...

, and

Zambia Zambia, officially the Republic of Zambia, is a landlocked country at the crossroads of Central Africa, Central, Southern Africa, Southern and East Africa. It is typically referred to being in South-Central Africa or Southern Africa. It is bor ...

. Citrine has been referred to as the "merchant's stone" or "money stone", due to a superstition that it would bring prosperity.

History

Quartz and its varieties have been used as gemstones for thousands of years. Citrine and other quartzes are believed to have been used by the

ancient Egypt Ancient Egypt () was a cradle of civilization concentrated along the lower reaches of the Nile River in Northeast Africa. It emerged from prehistoric Egypt around 3150BC (according to conventional Egyptian chronology), when Upper and Lower E ...

ians to make talismans, by the

ancient Greeks Ancient Greece () was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity (), that comprised a loose collection of culturally and linguistically re ...

for carving symbols, and by

Roman Roman or Romans most often refers to: *Rome, the capital city of Italy *Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of Roman civilization *Epistle to the Romans, shortened to Romans, a letter w ...

priests as rings.

Queen Victoria Victoria (Alexandrina Victoria; 24 May 1819 – 22 January 1901) was Queen of the United Kingdom of Great Britain and Ireland from 20 June 1837 until Death and state funeral of Queen Victoria, her death in January 1901. Her reign of 63 year ...

was reportedly fond of the gemstone; many

brooch A brooch (, ) is a decorative jewellery item designed to be attached to garments, often to fasten them together. It is usually made of metal, often silver or gold or some other material. Brooches are frequently decorated with enamel or with gem ...

es and

pendant A pendant is a loose-hanging piece of jewellery, generally attached by a small loop to a necklace, which may be known as a "pendant necklace". A pendant earring is an earring with a piece hanging down. Its name stems from the Latin word ...

s featuring citrine survive from this era. In the centuries before modern minerology, citrine was frequently confused with topaz. It was common in many cultures to use the name "topaz" for any golden yellow stone. The name "citrine" was first used in English in the 14th century. Its popularity greatly increased once it was discovered citrine could be produced artificially by heating amethyst or smoky quartz.

References

{{Jewellery Trigonal minerals Quartz gemstones

Color

Differentiation

Origin

History

See also

References