Citrine: The quartz mineral Citrine information and pictures Advertising Information The Mineral citrine Citrine is the yellow to brownish-red variety of the mineral Quartz . It is a widely used as a gemstone, and after Amethyst it is the most popular Quartz gem. Most Citrine is formed by heat treating purple Amethyst . Citrine may also be produced by heat-treating Smoky Quartz from certain localities. In some Amethyst deposits, the Amethyst has been partially or fully changed over to yellow Citrine by natural means of heating. Natural Citrine, which is rare, is yellow to orange-yellow, and occurs in much lighter hues than the heat-treated material, which is dark orange-brown to reddish-brown. Virtually all heat-treated material has a reddish tint, whereas the natural specimens do not. Natural light yellow Citrine is often called "Lemon Quartz" on the gemstone market. Sometimes Citrine has a "smoky" hue to it, and can be borderlined between Citrine and Smoky Quartz , with either definition being correct. For additional information, see the gemstone section on Citrine . USES Citrine is known mainly for its use as a gemstone .

Gems are faceted for jewelry, and it is often used as an inexpensive substitute for Topaz . Citrine is also popular among mineral collectors, and small pieces and drusy plates are often sold to amateur collectors in gift shops. NOTEWORTHY LOCALITIES Natural Citrine is not common and occurs sparingly in many large Quartz deposits. Most commercial gem-grade material comes from Rio Grande do Sul and Minas Gerais, Brazil, but almost all of the Brazilian material is heat treated Amethyst . A classic exhausted locality for natural Citrine is Olkhovka in the Northern Ural Mountains, Russia. Other locations where natural Citrine is found is San Cristobal, Santander, Colombia; Lubumbashi in Katanga (Shaba), Congo (Zaire); Antananarivo Province, Madagascar; Salamanca, Spain; and Dauphine, France. In Boekenhoutshoek (Magaliesberg), Mkobola district, South Africa, a unique form of natural Citrine is found together with Amethyst that has a spiky overgrowth of small crystals popularly called "Cactus Quartz". Citrine: Citrine mineral information and data.

From citrina (color as yellow as citron). A variety of Quartz A yellow to yellow-orange or yellow-green variety of quartz. A yellow-green citrine crystal with smoky phantoms. A cut natural citrine from Norway A natural citrine from Salamanca, a classic citrine locality A yellow-green citrine crystal with smoky phantoms. A cut natural citrine from Norway A natural citrine from Salamanca, a classic citrine locality A yellow-green citrine crystal with smoky phantoms. A cut natural citrine from Norway A natural citrine from Salamanca, a classic citrine locality The cause of the color is still under debate. At least some citrine is colored by aluminum-based and irradiation-induced color centers related to those found in smoky quartz (Lehmann, 1972; Maschmeyer et al., 1980). Accordingly, transitions to smoky quartz (" smoky citrine ") exist, many citrines show smoky phantoms. Like smoky quartz, these types of citrines pale when heated above 200-500°C and turn yellow again when irradiated (Lehmann, 1970).

There appear to be at least two types of yellow Al-based color centers with different thermal stability (Schmetzer, 1988). Since the yellow color centers are often more stable than the smoky color centers, some smoky quartz can be turned into citrine by careful heating (Nassau and Prescott, 1977). Natural citrine as well as citrine produced by heating smoky quartz is dichroic in polarized light. It has also been suggested that iron is the cause of color, as artificial crystals grown in a iron-bearing solution turn out yellow. However, the dichroic behavior of the lab-grown crystals differs from that in natural citrine (Rossmann, 1994). Dichroism of citrine (right) compared to smoky quartz (left) and heated amethyst (center) Thermal behaviour of citrine (two crystals in the center), compared to heated amethyst and amethyst, when heated to 380°C An amethyst geode cut into 2 halves, the right one was heated to turn the amethyst into "citrine".

Dichroism of citrine (right) compared to smoky quartz (left) and heated amethyst (center) Thermal behaviour of citrine (two crystals in the center), compared to heated amethyst and amethyst, when heated to 380°C An amethyst geode cut into 2 halves, the right one was heated to turn the amethyst into "citrine". Dichroism of citrine (right) compared to smoky quartz (left) and heated amethyst (center) Thermal behaviour of citrine (two crystals in the center), compared to heated amethyst and amethyst, when heated to 380°C An amethyst geode cut into 2 halves, the right one was heated to turn the amethyst into "citrine". Note: Natural citrine is very rare. Large quantities of amethyst , usually of lesser quality, are heated to turn it yellow or orange and sold as "citrine." Because the color is now caused by finely distributed iron minerals (mostly hematite and goethite), heated amethyst is not citrine in the strict sense, and also shows no dichroism in polarized light.

Thin coatings of iron oxides on colourless quartz, as well as inclusions of yellow iron oxides ("limonite"), may simulate citrine. Quartz colored by inclusions, or coatings, of any kind is not called citrine. Other Information Health Risks: Citrine is a variety of quartz which is usually quite harmless unless broken or powdered. Broken crystals and masses may have razor-sharp edges that can easily cut skin and flesh. Handle with care. Do not grind dry since long-term exposure to finely ground powder may lead to silicosis. References for Citrine Reference List: Georgius Agricola (1546) "De Natura Fossilium" (Book VI). Dover reprint Mark Chance Bandy & Jean A. Bandy translation Dover Publications p. 120 Dana, 1892, 187 - "Syst. Min. 6th Ed" Chudoba, K. F. (1962) Some relations between the causes of amethyst, smoky quartz, and citrine colors as given by modern science. Mineralogicheskii Sbornik (Lvov): 16: 91-105.

Samoilovich, M.I., Tsinober, L.I., Kreishop, V.N. (1969) The nature of radiation-produced citrine coloration in quartz. Soviet Physics-Crystallography: 13: 626-628. Lehmann, G. (1972) Yellow color centers in natural and synthetic quartz. Physik der Kondensierten Materie: 13: 297-306. Nassau, K., Prescott, B.E. (1977) Smoky, blue, greenish yellow, and other irradiation-related colors in quartz. Mineralogical Magazine: 41: 301-312. Maschmeyer, D., Niemann, K., Hake, K., Lehmann, G., Räuber, A. (1980) Two modified smoky quartz centres in natural citrine. Physics and Chemistry of Minerals: 6: 145-156 Schmetzer, K. (1988) Thermal stability of yellow color centers in natural citrine.

Neues Jahrbuch für Mineralogie, Monatshefte: 2: 71-80. Rossman, G.R. (1994) Colored varieties of the silica minerals. In: Reviews in Mineralogy, Vol.29, Silica - Physical behavior, geochemistry and materials applications, Mineralogical Society of America. Pan, Y., Nilges, M.J., Mashkovtsev, R.I. (2008) Radiation-induced defects in quartz. II. Single-crystal W-band EPR study of a natural citrine quartz. Physics and Chemistry of Minerals: 35: 387-397. Internet Links for Citrine Bestcrystals.com . Citrine CT-205 Citrine Clusters, .10-.14 lb. in weight and approximately 1.25 - 1.5 inches long. Each one unique. Sold by the each. $4.95 CT-204 Citrine Clusters, .15-.19 lb. in weight and approximately 1.25 - 2 inches long. Each one unique. Sold by the each.

$5.95 CT-204 Citrine Clusters, .15-.19 lb. in weight and approximately 1.25 - 2 inches long. Each one unique. Sold by the each. $5.95 CT-203 Citrine Clusters, .20-.29 lb. in weight and approximately 2 - 2.5 inches long. Each one unique. Sold by the each. $8.95 CT-202 Citrine Clusters, .30-.39 lb. in weight and approximately 2 - 3 inches long. Each one unique. Sold by the each. $12.00 CT-201 Citrine Clusters, .40-.49 lb. in weight and approximately 2.5 - 3 inches long. Each one unique. Sold by the each. $16.00 CT-201 Citrine Clusters, .40-.49 lb. in weight and approximately 2.5 - 3 inches long. Each one unique. Sold by the each. $16.00 CT-201A Citrine Clusters, .50-.59 lb.

in weight and approximately 2.5 - 3 inches long. Each one unique. Sold by the each. $18.00 CT-1a Citrine Crystals, approximately 2.5 - 2.75 inches long. Each one unique. Sold by the each. $10.95 Ametrine: A Bicolor Gemstone of Amethyst and Citrine Ametrine A bicolor quartz gemstone consisting of amethyst and citrine Ametrine: Beautiful ametrine gemstones. The center stone is a traditional 50/50 split of amethyst and citrine. The stones on the left and right are artistic cuts that allow light entering the stone to pass through purple amethyst and yellow citrine and blend into beautiful shades of orange, magenta, peach, and a range of other colors. Images courtesy of Minerales y Metales del Oriente S.R.L. and Ametrine.com . Faceted ametrine: Ametrine has traditionally been faceted in the emerald cut with approximately 1/2 of the stone composed of citrine, 1/2 composed of amethyst, and the dividing line between the color zones perpendicular to the table.

This stone has been cut to display the two colors of quartz. It is a 12x8 millimeter emerald-cut ametrine weighing approximately 3.5 carats. What is Ametrine? Most people have never heard of ametrine and are very surprised to see purple and yellow in a single transparent gemstone. Ametrine is a rare gemstone with a finite supply that is produced in commercial quantities at only one mine in the world. It is a relative newcomer to the gemstone trade, being available in small quantities for just a few decades. Ametrine is a variety of bicolor quartz that has zones of amethyst (purple) and citrine (golden yellow) in contact with one another in a single crystal. The words AMEthyst and ciTRINE were combined to yield the name "ametrine," which is widely used in the gemstone trade. This material is known by other less-frequently used names including: "amethyst-citrine," "trystine," "bicolor amethyst," "bicolor quartz," and "bolivianite." The bolivianite name is a response to the material being designated as the national gemstone of Bolivia .

Ametrine mine map: This map shows the geographic location of the Anahi ametrine mine in the Pantanal of eastern Bolivia. Where is Ametrine Produced? Ametrine is rarely found in nature. Almost all of the world's commercial ametrine production has been from the Anahi Mine in southeastern Bolivia. The mine has been operated by Minerales y Metales del Oriente S.R.L. since 1989. The Anahi Mine is in a dolomitic limestone of the Murcielago Group, a sequence of limestones up to 1500 feet thick that dip to the southwest in the area of the mine. Some zones within the Murcielago Group are heavily silicified, causing them to resist weathering and stand up above the surrounding Pantanal lowlands as prominent north-south-trending ridges. The Anahi Mine is in a ridge at a location where the dolomitic limestone is faulted and silicified. [1] Most of the mining activity is done underground, with a small amount of production at the surface. [2] Hydrothermal activity has facilitated the growth of quartz within fractures and vugs of the dolomitic limestone.

The walls of these openings are often covered with a thick layer of massive quartz with euhedral quartz crystals growing inwards towards the center of the cavities. Some of these are crystals of ametrine; many have been etched by later hydrothermal activity. Ametrine rough: A large piece of very high quality ametrine rough with beautiful richly colored amethyst and citrine in sharp contact with one another. A piece of rough like this could be used for cut stones or carvings. Photo courtesy of Minerales y Metales del Oriente S.R.L. and Ametrine.com . What Gives Ametrine Its Color? The colors of amethyst and citrine are produced by iron impurities with different oxidation states within the quartz. Purple is thought to be produced by Fe3+ that is oxidized to Fe4+ by natural radiation emitted by the decay of potassium-40 in nearby rocks. The golden-yellow is thought to be produced by Fe3+. [3] If a well-formed ametrine crystal is sawn perpendicular to the c-axis, the color zones of amethyst and citrine often form a geometric pattern that radiates outwards from the c-axis like the pieces of a pie.

Straight-line contacts separate zones of amethyst from zones of citrine. This pattern is formed by Brazil law twinning in which two quartz crystals of different color are intergrown to form the bicolor gemstone. [4] It is very different from the bicolor zones of a tourmaline crystal which form by sequential crystallization. Ametrine crystal from the Anahi Mine in Bolivia. Photo courtesy of Minerales y Metales del Oriente S.R.L. and Ametrine.com . History of Ametrine According to legend, the Ayoreo Indian tribe of eastern Bolivia knew about the bicolor quartz crystals over 500 years ago. Perhaps the earliest formal documentation of natural quartz crystals with zonal coloring of purple and yellow is in a 1925 issue of American Mineralogist. These were basal sections of quartz crystals with color sectors alternating between purple and yellow. [5] Reports of a quartz gemstone of mixed purple and yellow color being produced anywhere in the world begin in the 1960s from vague localities in Brazil, Bolivia, and Uruguay. Because the material was not attributed to a specific mine, some people believed it was produced synthetically, produced by treating amethyst, or mined illicitly.

[1] In 1989, changes to Bolivian mining laws allowed gemstone mining in eastern Bolivia, and a company, Minerales y Metales del Oriente S.R.L., obtained exclusive mining rights to a few thousand acres. Their property included a mine location with evidence of a long history of illicit mining. To establish credibility in the gemstone trade, the company invited geologists and gemologists to the mine and allowed them to confirm for themselves that the ametrine and citrine produced there were natural. Today, their Anahi Mine is the world's only important commercial source of natural ametrine and anahite (a clear variety of quartz with a very light tint of lilac). The mine also produces amethyst, citrine, and bicolor materials that are a combination of amethyst and clear quartz (bicolor amethyst) or citrine and clear quartz (bicolor citrine). Ametrine faceting rough: Rough ametrine that has been sawn into pieces that are ready for cutting faceted stones. Photograph courtesy of GemFacetingRough.com .

Byproducts of ametrine mining - amethyst, citrine, and bicolor stones: The Anahi Mine produces ametrine but also amethyst, citrine, bicolor amethyst and bicolor citrine. Samples of these materials are shown above. They are sawn to produce pieces that are ready for faceting. Photograph courtesy of GemFacetingRough.com . Ametrine Gemstones A crystal containing both amethyst and citrine in contact with one another can be called "ametrine." These crystals usually contain zones of clear quartz, amethyst, and citrine. When these crystals are cut into pieces that are appropriately sized for faceting gemstones, only a portion of the stones will be ametrine. The remainder will be amethyst, citrine, and clear quartz. This is why the Anahi Mine produces a variety of gem materials and why the amount of ametrine produced is limited. Some of the early people involved in illicit production from the Anahi mine site were intent to produce amethyst and citrine.

The novelty of a bicolor gemstone began when some lapidaries, inspired by bicolor tourmaline, began producing emerald-cut stones that were 50% amethyst and 50% citrine with the color boundary oriented perpendicular to the table of the stone. These stones were very attractive and desirable to people who saw them. The bicolor material then became a focus of production. When Minerales y Metales del Oriente S.R.L. took over the mine, much of the production was being sold as cutting rough and mineral specimens. Since then the owner has worked to diversify revenue by developing the staff and facilities needed to cut the stones, design jewelry, manufacture jewelry, and market the rough, the loose stones, and finished jewelry. Now a large portion of the world's ametrine gemstones are taken from the Earth and delivered to the end consumer through a few related companies located in Bolivia. [2] New methods of cutting have been developed to make maximum use of a finite ametrine resource. Some stones are still cut in the traditional emerald cut with a 50/50 amethyst/citrine split.

Others are cut into "blended ametrine" that has random or planned patches of amethyst and citrine. These stones are cut in orientations that allow light penetrating the stone to pass through zones of purple amethyst and golden-yellow citrine. This can yield beautiful stones with face-up colors that include peach, magenta, and orange. Physical Properties of Ametrine Gemstone Synthetic / Treatment-Created "Ametrine" Laboratory experiments in 1981 determined that heat and irradiation can be used to convert natural amethyst into a bicolor material that has an appearance similar to natural ametrine. [6] This process is costly to do well and is not known to have produced a significant amount of treatment-created "ametrine." In 1994 a laboratory in Russia began producing small quantities of synthetic bicolor quartz from alkaline solutions using a hydrothermal process. This synthetic material is being cut, mounted in jewelry and sold in the Russian jewelry market. [7] Some is being exported to other countries and sold as "ametrine." Most of this material has a coloration that an experienced person would immediately recognize as synthetic and not confuse with natural ametrine even though the name is being used.

More Information About Ametrine [1] The Anahi Ametrine Mine, Bolivia : Paulo M. Vasconcelos, Hans-Rudolf Wenk, and George R. Rossman; Gems & Gemology, Volume 30, Number 1, Spring 1994, pages 4-23. [2] Ametrine.com : the official website of Minerales y Metales del Oriente S.R.L., owners of the Anahi Mine, Bolivia. [3] Ametrine : George Rossman, article on the Mineral Spectroscopy Server, California Institute of Technology, 2012. [4] Quartz (Var: Ametrine) : Brian Kosnar, photograph and description published on Mindat.org as photo of the day for February 12, 2010. [5] The Cause of Color in Smoky Quartz and Amethyst : Edward Holden, American Mineralogist, Volume 9, pages 203-252, 1925.

[6] Artificially Induced Color in Amethyst-Citrine Quartz : Kurt Nassau, Gems & Gemology, Volume 17, Number 1, Spring 1981, pages 37-39. [7] Russian Synthetic Ametrine : Vladimir S. Balitsky, Taijin Lu, George R. Rossman, Irina B. Makhina, Anatolii A. Mar'in, James E. Shigley, Shane Elen, and Boris A. Dorogovin; Gems and Gemology, Volume 35, Number 2, Summer 1999, pages 122-134. Anyone Can Own Ametrine If you search online or go to a jewelry store that has a nice selection of colored stone jewelry, you might find a few pieces of ametrine for sale. The price is usually inexpensive when compared to other stones of similar size and beauty - certainly less expensive than bicolor tourmaline. Almost anyone who can afford to purchase jewelry is able to obtain a beautiful item with an ametrine gemstone of reasonable size. They are bargains when the beauty of the stones and the rarity of the material are compared to their price.

Amethyst Quartz: The purple gemstone Amethyst information and pictures Amethyst ON EBAY ALL ABOUT Amethyst is the purple variety of the mineral Quartz , and is its most famous and valuable gem variety. Quartz also contains other gemstones such as Citrine , Rose Quartz , and Smoky Quartz . The color of Amethyst is most often caused by iron impurities , though it can also be colored by natural radiation exposure. Amethyst is sometimes heat treated to deepen the color, or to transform it into Citrine . Some forms of Amethyst may also change to a light green color upon heat treatment, and such stones are given the name Prasiolite , or " Green Amethyst ", as it is more commonly known in the gem trade. Amethyst comes from many different mining sources, some of which produce distinct color styles. For example, Amethyst from Uruguay has a deep purplish-blue color, as does Amethyst from Arizona. Amethyst from Russia, colloquially known as "Siberian Amethyst", is very deeply colored with reddish and bluish tints. It originates from deposits that have since been exhausted and therefore command a high price.

Some dealers may sell deeply colored Amethyst from other locations as "Siberian Amethyst" to generate a higher selling value. African Amethyst is generally more deeply colored than South American Amethyst, and the label "African Amethyst" in the gem trade may be improperly used to describe a deeper color stone even if it didn't originate in Africa. The color distribution of Amethyst is sometimes uneven, and this is often taken into account when cutting a stone. Care should also be taken with Amethyst as it is known to form curve shaped fractures if banged too hard. Some Amethyst from a few locations may slightly fade in color upon prolonged exposure to light. Amethyst can occur in huge flawless crystals, and gems of all sizes have been faceted . Due to the abundance of Amethyst, it is usually clean and free of flaw s or inclusion s. Because of this, Amethyst with any visible flaws or inclusions should be avoided. A natural mixture of purple Amethyst and golden Citrine has been coined with the trade name "Ametrine".

(See the dedicated page for Ametrine page for more details.) USES Amethyst is faceted into many cuts, and is used in all forms of jewelry including rings, necklaces, earrings, bracelets, and pendants. Many large gems weighing several hundred carat s have been cut from Amethyst. Ornamental objects are occasionally also carved from large pieces. Lower quality Amethyst is an important bead gem and can also be cut into cabochon s. Tumbled beads of purple Amethyst mixed with white Quartz are also used as necklaces and bracelets. Amethyst is the birthstone of February. Amethyst TREATMENTS AND ENHANCEMENTS Amethyst is sometimes heat treated to deepen the purple color and transform lighter colored stones into deeper hues. More often though, Amethyst is heat treated to produce Citrine and the green Quartz known as Prasiolite . Although Amethyst sources are abundant, synthetic Amethyst gems are also produced using the hydrothermal method . Amethyst SOURCES Brazil is the largest producer of Amethyst. It is found there in the states of Minas Gerais, Rio Grande do Sul, Maraba and Bahia.

Other important deposits are in Uruguay (in Artigas), Argentina, Bolivia, Mexico, Namibia, Zambia, South Africa, Madagascar, Canada (Ontario), and the United States (Arizona, North Carolina, Georgia, and Maine). A specific deposit of Amethyst known to produce the greenish Prasiolite variety upon heat treatment is the Montezuma Mine in Minas Gerais, Brazil. SIMILAR GEMSTONES The color of Amethyst is rather unique, and few gems are confused with it, especially in deeper shades. Purple Sapphire and Purple Spinel may be the same color of Amethyst, but these are both very rare and command much higher prices than Amethyst. Iolite may also be similar but has a bluer hue. Fluorite can have the same color, but its very low hardness limits its use as a gemstone and it is only used as a collectors gem. Amethyst PHOTOS [Click photos for more details] Amethyst JEWELRY PHOTOS [Click photos for more details] Quartz | Minerals Education Coalition Return to Minerals Database Quartz Quartz is one of the most common minerals in the Earth’s crust.

As a mineral name, quartz refers to a specific chemical compound (silicon dioxide, or silica, SiO2), having a specific crystalline form (hexagonal). It is found is all forms of rock: igneous, metamorphic and sedimentary. Quartz is physically and chemically resistant to weathering. When quartz-bearing rocks become weathered and eroded, the grains of resistant quartz are concentrated in the soil, in rivers, and on beaches. The white sands typically found in river beds and on beaches are usually composed mainly of quartz, with some white or pink feldspar as well. Type conchoidal Description Quartz is one of the most common minerals in the Earth’s crust. As a mineral name, quartz refers to a specific chemical compound (silicon dioxide, or silica, SiO2), having a specific crystalline form (hexagonal). It is found is all forms of rock: igneous, metamorphic and sedimentary. Quartz is physically and chemically resistant to weathering. When quartz-bearing rocks become weathered and eroded, the grains of resistant quartz are concentrated in the soil, in rivers, and on beaches.

The white sands typically found in river beds and on beaches are usually composed mainly of quartz, with some white or pink feldspar as well. Relation to Mining Quartz crystal is found in many countries and many geologic environments. Major producers of natural quartz crystals are the United States (particularly Arkansas) and Brazil. Natural quartz is rarely used as found in nature (especially in electrical applications), except as a gemstone. Natural quartz crystals have too many chemical impurities and physical flaws. As a result, a commercial process of manufacturing pure, flawless, electronics-grade quartz was developed. “Cultured quartz,” that is, quartz crystals grown very carefully in highly controlled laboratory conditions, is the quartz that is used in industry. About 200 metric tons of cultured quartz is produced each year. In the production of cultured quartz crystals, a “seed crystal” is needed. A seed crystal is a small piece of carefully selected, non-electronics-grade quartz. The manufactured crystal grows on this seed crystal. Uses Quartz crystal is one of several minerals which are piezoelectric, meaning that when pressure is applied to quartz, a positive electrical charge is created at one end of the crystal and a negative electrical charge is created at the other.

These properties make quartz valuable in electronics applications. Electronics-grade manufactured quartz is used in a large number of circuits for consumer electronics products such as computers, cell phones, televisions, radios, electronic games, etc. It is also used to make frequency control devices and electronic filters that remove defined electromagnetic frequencies. Amethyst Factsheet and Amethyst Mineral Information QUARTZ (Amethyst) BACKGROUND INFORMATION Amethyst is a macrocrystalline variety of the mineral Quartz (SiO2). Quartz is the most abundant single mineral on earth. It makes up about 12% of the earth's crust, occurring in a wide variety of sedimentary, igneous and metamorphic rocks. Quartz varieties are commonly separated into two groups based on the size of the individual grains or crystals; macrocrystalline quartz in which individual crystals are distinguishable with the naked eye, and cryptocrystalline quartz in which the individual crystals are too small to be easily distinguishable under the light microscope. Some of the macrocrystalline quartz varieties are: amethyst , Ametrine , Cat's-eye Quartz , Citrine , Phantom Quartz , Rock Crystal , Rose Quartz , Rutilated Quartz , Smoky Quartz and Strawberry Quartz .

Blue Aventurine Quartz and Green Aventurine Quartz are actually quartzites (a rock, not a mineral) composed essentially of interlocking macrocrystalline quartz grains with disseminated grains of other color imparting minerals. The cryptocrystalline varieties of quartz may be separated into two types; fibrous and microgranular. Chalcedony is the general term applied to the fibrous cryptocrystalline varieties. Agate is a well known example of a fibrous cryptocystalline banded chalcedony variety of quartz. Carnelian, Chrysoprase and bloodstone are other chalcedony varieties. Chert is the general term applied to the granular cryptocrystalline varieties of quartz, of which Jasper and flint are examples. AMETHYST OCCURRENCE INFORMATION AND DIAGNOSTIC FEATURES Amethyst has been found in siliceous volcanics, occurring as macroscopic crystals and drusy coverings inside of agate and chalcedony lined amygdaloidal cavities or vugs, often forming geodes. Amethyst also occurs in quartz veins.

The purple color of amethyst is due to small amounts (approximately 40 parts per million) of iron (Fe4+) impurities at specific sites in the crystal structure of quartz. The difference between amethyst and citrine is only the oxidation state of the iron impurities present in the quartz. Upon heating, the iron impurities are reduced and amethyst's purple color fades and becomes yellow to reddish-orange (citrine), green, or colorless depending on the site and original oxidation state of the iron impurities present and the amount and duration of the heating. The amethystine color usually can be regained by irradiation which re-oxidizes the iron impurities. This irradiation can be done by synthetic means, or it can occur in nature by radioactive decay of nearby radioactive minerals. In most cases this is a reversible process, however excessive heating may change the distribution of the iron impurities at the different sites within the quartz making it impossible to convert it back to amethyst by subsequent irradiation. The heating process can occur naturally or synthetically. At the present, it is not possible to determine whether or not an amethyst or citrine was synthetically irradiated or heated.

Amethyst is recognized by its color, crystal habit, occurance, hardness, glassy luster, conchoidal fracture and lack of cleavage. AMETHYST HISTORICAL INFORMATION AND USES Amethyst has been used as gemstones and other ornamental objects for thousands of years. The early Greeks believed that amethyst would protect one from the effects of drunkenness when consuming alcohol. A possible explanation for this unusual virtue being given to amethyst is that when water is poured into a cup fashioned of amethyst, it would have the appearance of wine yet could be drunk without experiencing wine's normal inebriative effect. In ancient cultures, amethyst amulets were worn as antidotes against poison, to dispell sleep, as protection against harm in battle and to sharpen one's wits. In medieval times, amethyst was still credited with protecting one from the effects of drunkenness, both of the cup and also from the intoxicating effects of being in love. The wearing of amethyst was also known to protect soldiers from harm and give them victory over their enemies, and assist hunters with the capture of wild animals. The name amethyst comes from the Greek word amethustos which means not drunken.

In the first century, Pliny wrote that amethyst was so named for its color being nearly the same as that of wine. Early Greeks believed that drinking wine from an amethyst cup would prevent intoxication. The astrological signs of amethyst are Pisces, Virgo, Aquarius and Capricorn. Amethyst jewelry is the traditional birthstone gift for the month of February. Amethyst is the symbolic gemstone for the 17th wedding anniversary. AMETHYST METAPHYSICAL PROPERTIES Amethyst Crystals are said to bring serenity and calm, to enhance one's ability to assimilate new ideas, and to assist during meditation. Amethyst is also said to give strength and mental stability, and to provide balance between one's physical, emotional, intellectual states. Wearing amethyst jewelry is also said to make one shrewd in business matters. Amethyst is said to help remove toxins from the body and to help treat arthritus. It also said to be usefull in treating a number of disorders including those of the digestive system, heart, nervous system, skin and hearing and to help provide relief from pain and to strengthen the immune system.

For more in-depth metaphysical information, Citrine — Crystal Meanings "Kundalini Quartz" Natural Congo Citrine Example Alternate Names & Name Spellings: Success Stone, Merchant's Stone, Citrina, Citron Crystals Meanings of Citrine Keywords: Success, Abundance, Personal Power Citrine is a joyful stone with bright energy which lights up many aspects of lives of those who work with it. It has energies of good fortune and good luck, though these may appear in unexpected ways. Citrine is well known in crystal work as a success and prosperity stone to the point that it is called the "Success Stone." It is said to promote and manifest success and abundance in all areas, and in many ways. It is particularly used to promote success in business if used in the cash box of a shop, carried or worn, earning it another nickname, "Merchant's Stone." In addition to manifesting abundance, citrine also brings energies of generosity so that the prosperity and success is shared. Citrine is a solar plexus chakra stone used metaphysically to increase, magnify and clarify personal power and energy. This increased personal power can be used for the focused intent of the individual, as it brings will power as well.

Citrine is a fabulous stone to use to combat negative energy of any kind by breaking them up and dissipating them. It is helpful to clear unwanted energies from the environment, whether it be home, office, car, or other space indoors or out. Family issues caused by negative energies can also be cleared for resolution with citrine. Citrine is also a stone that brings hope. Since citrine eliminates negative energies, it is good for protection in general and helps bring stability energetically. Citrine also does not absorb any negative energies from its surroundings, and thus never needs energetic clearing. Because citrine can clear negative energy and influences from the aura, it is useful for meditation, psychic awareness, and spiritual development. By removing unwanted energies it paves the way for this spiritual and psychic growth. It is also excellent for dream recall and dream work. In the mental arena, citrine enhances mental clarity, confidence, and will power. The mental clarity and confidence support bringing increased creativity and honesty. Since citrine brings self-confidence as well as positive energy, it can also help eliminate fears of being judged or of others' ideas. It is also used to dissipate fear of being alone or unworthy of love. Citrine is a happy stone.

It can bring happiness to the person who carries or wears it. Because of its removal of negative energy and its own bring positivity, it can relieve depression, self-doubt, anger, and irrational mood swings. Citrine is used to reduce self-destructive tendencies. Citrine can help overcome emotional traumas and grief that may lead to these emotionally self-destructive issues. In crystal healing and healing folklore, citrine is said to be beneficial for the digestion, stomach, nightmares, other sleep disturbances, thyroid, general health, heart, kidney, liver, muscles, strength, endocrine system, circulatory system, tissue regeneration, urinary system, immune system, diabetes, fibromyalgia. Citrine is also reputed to be good for removing toxins, and overcoming addictions. Sensuality and sexuality can also be heightened by citrine making it a stone of positive choice for sexual issues. Note that healing crystal meanings are spiritual supports to healing and are not prescriptions or healthcare information. Citrine is associated primarily with the solar plexus chakra . Citrine is yellow/gold quartz. See the Quartz page for mineral data, and additional metaphysical properties and healing properties common to all quartz stones.

More on Citrine, from My Personal Perspective Perspectives and opinions are often sharply divided as to whether natural and heat treated citrine have the same metaphysical properties. I feel that if nothing else, they have very similar energy due to correspondences of color energy and energetic intent on the part of those using it. Additionally, heat treating amethyst into a citrine color is the manmade version of what mother nature does herself. Like no two crystals growing next to each other in the earth have exactly the same energy, neither would natural and man-heat treated citrine, though they would be similar. One of the primary differences I've found over the years is that the energy of the natural stones seems a bit more focused to me. Working with the intent of doing the highest good for all concerned can ameliorate the mildly scattered feeling of heat treated citrine. Since this is something an energy worker or crystal healer would normally do in the course of his or her efforts it's not an onerous task to take on to smooth out the energy of any crystal including citrine. "In some Amethyst deposits, the Amethyst has been partially or fully changed over to yellow Citrine by natural means of heating.

- See more at: " The Quartz Page: Citrine 1178x1006 147kb 20mm 1176x1006 107kb The two pictures to the right show a citrine crystal from Hasawarka, Russia. When illuminated directly from the front, the crystal appears very dark and almost green. But when the crystal is illuminated from behind, its real color is revealed: a deep and homogeneously distributed yellow. In jewelery, faceted citrine used to be sold as "gold topaz". I don't know if that is still common practice, but as far as I know the traders codex does not allow this anymore. On this web site, I do not call quartz citrine if it is yellow because of inclusions of iron oxide minerals, but ferruginous quartz or "eisenkiesel". Thus I use a different definition: Citrine is a transparent yellow quartz variety whose color is caused by colorizing agents that are built into the crystal lattice and whose color is not caused by inclusions of other minerals. I do this for reasons of consistency in the naming, but by gemologists' standards it is o.k.

to call a quartz with finely distributed iron minerals, including heat-treated amethysts, a "citrine". If you checked different sources in books and in the Internet, the explanation for the yellow color that is almost exclusively given is: traces of iron. However, there seem to be at least 2 kinds of citrine that differ in the cause of the color and possibly in their inner structure (see "Specific Properties"). Specific Properties Going through the literature to learn about the causes of the greenish-yellow, yellow or orange color is leaving an impression that there are at least 2 different yellow quartz varieties, and at least 3 if you count heat treated amethyst. Whatever the cause of the color and however much people differ on what qualifies as "citrine", the common denominator seems to be that the colorizing agent should be more or less evenly and finely distributed in the crystals and that the crystals should appear transparent. Nobody calls a yellow but opaque crystal or a clear crystal with yellow grainy or fibrous inclusions a citrine. Note: the following names "aluminum citrine" and "iron citrine" are not officially approved, I just made them up as a convenient label.

"Aluminum Citrine" Like the color of smoky quartz, the color of this type of citrine is caused by irradiation and traces of aluminum built into its crystal framework. The yellow can be very deep with shades of green, but usually is a little pale. This citrine shows a very weak dichroism, that is, its color changes a bit depending on the angle of the incoming light (see Physical Properties for an explanation). This citrine will actually loose its color upon heating to more than 200°C, and the yellow color will occur again when the crystal is irradiated with x- or gamma-rays. This is not the case for heat treated amethyst (see below), which turns yellow at - very high - temperatures that will turn natural citrine white. Some smoky quartz from certain locations (e.g. Peterson Mountain, Nevada) shows a yellow tone in parts of its crystals. Some yellowish smoky quartz can even be turned into citrine by careful heating, because the color centers in citrine are more stable and the smoky color disappears before the yellow. "Aluminum citrine" is usually evenly colored, though "phantoms" of smoky quartz are found occasionally.

It is probably impossible to distinguish heat treated smoky quartz from true citrine, as it is impossible to identify an artificially irradiated citrine. You have to check reports about the location to be sure. Why citrine turns out yellow and not smoky despite the fact that the same trace elements are built in is still a matter of debate. In studies on Brazilian quartz crystals that were artificially irradiated to determine high-purity specimen for industrial use, Jung, 1992 , found that the ratio of the amount of aluminum and the amount of lithium built into the crystal lattice is possibly a critical factor. Crystals with a Li:Al ratio of close to 1 will assume the typical smoky quartz or black (morion) color upon irradiation, whereas crystals with a Li:Al ratio of about 0.5 will assume a honey color and those with a Li:Al ratio of less than 0.3 will turn yellow. The depth of the color varies with the absolute amount of Li and Al, and the yellow may be faint or very dark. This type of citrine can basically appear in the same crystal habits and crystal forms as rock crystal or smoky quartz, but good crystals are said to be rare.

It can show accessorial crystal faces, like the dipyramidal s- or the trapezoidal x-face, just like rock crystal and smoky quartz. A citrine showing these faces is most likely not a heat treated amethyst. "Iron Citrine" Quartz crystals artificially grown from a hot watery silica solution (hydrothermal synthesis) turn out yellow if iron compounds are added to the solution. The iron seems to be incorporated into the crystal lattice. Although these quartzes sometimes lack the polysynthetical twinning that is common in natural amethyst, they are converted into amethysts by irradiation. It is likely that at least some of the natural citrines fall into the same category. "Heated Amethyst" 1050x929 138kb It used to be quite common to produce "citrine" by heating amethyst. For this the amethyst does not need to have a deep color, faint or almost gray specimen may also assume a deep yellow or orange color upon heating. Once offered in great amounts, crystallized mineral specimen treated in such a way have actually almost disappeared from fairs, as collectors apparently don't want to pay that much for something that has been artificially altered.

Heat treated amethyst is sold by the lot as "citrine" for lapidary purposes. As the distribution of color of amethyst is very different from that of most natural citrine, a heat treated amethyst is easily recognized: the yellow color is most intense in the tips, and the color might be more concentrated under the r-rhombohedra or patchy. Yellow or orange quartz in druzy geodes is most likely - and I would tend to say always - heated amethyst. Goethite inclusions are very suspicious, of course. On the other hand, citrine crystals showing accessorial faces can hardly be heat treated amethyst. If the crystal is clear, you can check for dichroism: natural citrine is often slightly dichroic, whereas heated amethyst is not (see Physical Properties for a method to check this). Note: according to the lapidary traders codex it is o.k. to call heat treated amethyst citrine. Occurrence Citrine occurs in the same environments as smoky quartz, mostly intrusive igneous rocks which contain traces of radioactive elements whose radiation cause the coloration. Locations and Specimen Citrine is a rare quartz variety.

It is found in good quality in Brazil, Madagascar, and Russia. Recently artichoke like crystals from Kongo have shown up on fairs. Very few locations in the Alps (all in Austria) have yielded citrine, the already rare alpine amethyst is much more common. There are also a couple of locations of smoky quartz with shades of yellow, Peterson Mountain a.k.a. Hallelujah Junction has already been mentioned. Brazil 801x1006 67kb - 1602x2012 209kb This citrine comes from Minas Gerais, Brazil. The friendly trader told me it would actually be a "Brasilit" (German spelling), and very likely had been subject to some treatment. "Brazilite" is a synonym of baddeleyite, ZrO 2 2 . I couldn't find out anything more about "Brasilit" than it might possibly be a name for honey colored citrine. This specimen is not honey colored like what I saw on the few pictures on the Internet, but more lime colored. The honey colored material looked a bit like heated amethyst to me.

The specimen shown here is almost certainly not a heated amethyst, because there is a small s-face on one of the crystals. So the only possibilities I could think of would be a moderately heated smoky quartz or an irradiated rock crystal. I've shown the specimen to an mineralogist and to an expert for jewelery, but both hadn't heard of an actual use of such treatments, and of course, there are no hints within the crystal itself that point to anything like moderate heating or irradiation. You can't tell just by looking at it, as you can with heat treated amethyst. Meanwhile I'm pretty sure it's a natural citrine. 20mm 800x1024 79kb - 1600x2048 226kb Citrines with a typical artichoke quartz habit have recently appeared on the market, first very few of them, but batches of large crystals since 2006. They are found in weathered rock at small scale mining operations at Lueni, Katanga province. Most crystals are at least a bit smoky in color. One can frequently see faint smoky phantoms.

Their most characteristic feature is the candle quartz habit (some would call it artichoke quartz habit) that apparently can be found in all specimen from that location. A more smoky specimen is shown at the growth form section . Citrine of similar habit is said to come from the Andes mountains. Kazakhstan 652x917 62kb - 1303x1834 209kb This crystal from Akjaylan in eastern Kazakhstan shows several smoky layers parallel to the large rhombohedral face. It has been found in a pegmatite and there is still some mica attached at the crystal's base. It is also a very nice demonstration of what the stripes on the prism come from: it's just a pattern of alternating rhombohedra and prisms, the last stair step being visible at the crystal tip. Madagascar 690x980 60kb This crystal from Anjoma, Madagascar, shows a citrine phantom underneath a clear smoky tip and serves as another example of a combined citrine/smoky quartz. The yellow color is most intense at the base of the crystal.

Namibia 1128x1048 155kb - 2256x2096 450kb A clear and very pale citrine crystal on microcline feldspar from a miarole pocket in granite at the western Erongo mountains. The crystal would qualify as a stubby Tessin or transitional habit crystal. Its surface is etched, as many crystals from pegmatite and miarole pockets. Russia 1088x1496 167kb - 2176x2992 558kb The specimen to the right is the same jewelery grade citrine shown on the pictures on top of the page (found at Hasawarka in the Ural mountains) from a different perspective, and partially illuminated from the back so one can see its dark yellow color. It looks very different from the burnt amethyst you usually get, with a dark homogeneous color and nicely developed prisms. The prism shows an interesting pattern of lines parallel to the planes of the rhombohedra, leading to a mosaic of triangles.

This pattern is very likely due to a Brazil law twinning of the crystal that has been revealed by natural etching. 20mm 800x960 67kb - 1600x1920 218kb A pale citrine-colored scepter from Peterson Mountain, California/Nevada. This crystal is slightly dichroic (I thought it is not, but I checked again and it is). It appears to be not perfectly clear, but the latter is in part due to the fact that the crystal's surface has been etched naturally. The crystal has spent several days in HCl and has been brushed thoroughly, so the color is not caused by a superficial stain of limonite. Judging from the tone of the color and my erroneous belief that the crystal is not dichroic, my first guess was that the color is caused by iron, either embedded in compounds or built into the crystal lattice. And since this crystal has been found in a small pocket in the same granite that produces smoky quartz, and thus has been subject to prolonged high energy radiation, I wondered why it is not purple like the many other amethyst found at that locality and speculated that this is a ferruginous quartz.

After I have checked the crystal again and found that the crystal is dichroic, I would say that this is probably a true citrine.

Question: Citrine and amethyst are forms of what mineral?
Answer: Quartz