All species of garnets possess similar physical properties and crystal forms, but differ in chemical composition. The different species are pyrope, almandine, spessartine, grossular (varieties of which are hessonite or cinnamon-stone and tsavorite), uvarovite and andradite. The garnets make up two solid solution series: pyrope-almandine-spessartine and uvarovite-grossular-andradite.
|The general formula X3Y2(SiO4)3|
|Color||virtually all colors, blue very rare|
|Crystal habit||Rhombic dodecahedron or cubic|
|Fracture||conchoidal to uneven|
|Mohs scale hardness||6.5–7.5|
|Luster||vitreous to resinous|
|Polish luster||vitreous to subadamantine|
|Optical properties||Single refractive, often anomalous double refractive|
|Other characteristics||variable magnetic attraction|
The word garnet comes from the 14th‑century Middle English word gernet, meaning 'dark red'. It is derived from the Latin granatus, from granum ('grain, seed'). This is possibly a reference to mela granatum or even pomum granatum ('pomegranate', Punica granatum), a plant whose fruits contain abundant and vivid red seed covers (arils), which are similar in shape, size, and color to some garnet crystals.
Garnet species are found in many colors including red, orange, yellow, green, purple, brown, blue, black, pink, and colorless, with reddish shades most common.
Garnet species' light transmission properties can range from the gemstone-quality transparent specimens to the opaque varieties used for industrial purposes as abrasives. The mineral's luster is categorized as vitreous (glass-like) or resinous (amber-like).
Garnets are nesosilicates having the general formula X3Y2(SiO4)3. The X site is usually occupied by divalent cations (Ca, Mg, Fe, Mn)2+ and the Y site by trivalent cations (Al, Fe, Cr)3+ in an octahedral/tetrahedral framework with [SiO4]4− occupying the tetrahedra. Garnets are most often found in the dodecahedral crystal habit, but are also commonly found in the trapezohedron habit. (Note: the word "trapezohedron" as used here and in most mineral texts refers to the shape called a Deltoidal icositetrahedron in solid geometry.) They crystallize in the cubic system, having three axes that are all of equal length and perpendicular to each other. Garnets do not show cleavage, so when they fracture under stress, sharp irregular pieces are formed (conchoidal).
Because the chemical composition of garnet varies, the atomic bonds in some species are stronger than in others. As a result, this mineral group shows a range of hardness on the Mohs scale of about 6.5 to 7.5. The harder species like almandine are often used for abrasive purposes.
For gem identification purposes, a pick-up response to a strong neodymium magnet separates garnet from all other natural transparent gemstones commonly used in the jewelry trade. Magnetic susceptibility measurements in conjunction with refractive index can be used to distinguish garnet species and varieties, and determine the composition of garnets in terms of percentages of end-member species within an individual gem.
Almandine, sometimes incorrectly called almandite, is the modern gem known as carbuncle (though originally almost any red gemstone was known by this name). The term "carbuncle" is derived from the Latin meaning "live coal" or burning charcoal. The name Almandine is a corruption of Alabanda, a region in Asia Minor where these stones were cut in ancient times. Chemically, almandine is an iron-aluminium garnet with the formula Fe3Al2(SiO4)3; the deep red transparent stones are often called precious garnet and are used as gemstones (being the most common of the gem garnets). Almandine occurs in metamorphic rocks like mica schists, associated with minerals such as staurolite, kyanite, andalusite, and others. Almandine has nicknames of Oriental garnet, almandine ruby, and carbuncle.
Pyrope (from the Greek pyrōpós meaning "fire-eyed") is red in color and chemically an aluminium silicate with the formula Mg3Al2(SiO4)3, though the magnesium can be replaced in part by calcium and ferrous iron. The color of pyrope varies from deep red to black. Pyrope and spessartine gemstones have been recovered from the Sloan diamondiferous kimberlites in Colorado, from the Bishop Conglomerate and in a Tertiary age lamprophyre at Cedar Mountain in Wyoming.
A variety of pyrope from Macon County, North Carolina is a violet-red shade and has been called rhodolite, Greek for "rose". In chemical composition it may be considered as essentially an isomorphous mixture of pyrope and almandine, in the proportion of two parts pyrope to one part almandine. Pyrope has tradenames some of which are misnomers; Cape ruby, Arizona ruby, California ruby, Rocky Mountain ruby, and Bohemian garnet from the Czech Republic. Another intriguing find is the blue color-changing garnets from Madagascar, a pyrope-spessartine mix. The color of these blue garnets is not like sapphire blue in subdued daylight but more reminiscent of the grayish blues and greenish blues sometimes seen in spinel. However, in white LED light, the color is equal to the best cornflower blue sapphire, or D block tanzanite; this is due to the blue garnet's ability to absorb the yellow component of the emitted light.
Spessartine or spessartite is manganese aluminium garnet, Mn3Al2(SiO4)3. Its name is derived from Spessart in Bavaria. It occurs most often in granite pegmatite and allied rock types and in certain low grade metamorphic phyllites. Spessartine of an orange-yellow is found in Madagascar. Violet-red spessartines are found in rhyolites in Colorado and Maine.
Blue pyrope–spessartine garnets were discovered in the late 1990s in Bekily, Madagascar. This type has also been found in parts of the United States, Russia, Kenya, Tanzania, and Turkey. It changes color from blue-green to purple depending on the color temperature of viewing light, as a result of the relatively high amounts of vanadium (about 1 wt.% V2O3).
Other varieties of color-changing garnets exist. In daylight, their color ranges from shades of green, beige, brown, gray, and blue, but in incandescent light, they appear a reddish or purplish/pink color.
This is the rarest type of garnet. Because of its color-changing quality, this kind of garnet resembles Alexandrite.
Andradite is a calcium-iron garnet, Ca3Fe2(SiO4)3, is of variable composition and may be red, yellow, brown, green or black. The recognized varieties are topazolite (yellow or green), demantoid (green) and melanite (black). Andradite is found both in deep-seated igneous rocks like syenite as well as serpentines, schists, and crystalline limestone. Demantoid has been called the "emerald of the Urals" from its occurrence there, and is one of the most prized of garnet varieties. Topazolite is a golden-yellow variety and melanite is a black variety.
Grossular is a calcium-aluminium garnet with the formula Ca3Al2(SiO4)3, though the calcium may in part be replaced by ferrous iron and the aluminium by ferric iron. The name grossular is derived from the botanical name for the gooseberry, grossularia, in reference to the green garnet of this composition that is found in Siberia. Other shades include cinnamon brown (cinnamon stone variety), red, and yellow. Because of its inferior hardness to zircon, which the yellow crystals resemble, they have also been called hessonite from the Greek meaning inferior. Grossular is found in contact metamorphosed limestones with vesuvianite, diopside, wollastonite and wernerite.
Uvarovite is a calcium chromium garnet with the formula Ca3Cr2(SiO4)3. This is a rather rare garnet, bright green in color, usually found as small crystals associated with chromite in peridotite, serpentinite, and kimberlites. It is found in crystalline marbles and schists in the Ural mountains of Russia and Outokumpu, Finland.
Knorringite is a magnesium-chromium garnet species with the formula Mg3Cr2(SiO4)3. Pure endmember knorringite never occurs in nature. Pyrope rich in the knorringite component is only formed under high pressure and is often found in kimberlites. It is used as an indicator mineral in the search for diamonds.
|Mineral name||Formula||Crystal system||Point group||Space group|
|Mineral name||Formula||Crystal system||Point group||Space group|
|Hibschite||Ca3Al2(SiO4)(3-x)(OH)4x (x= 0.2–1.5)||isometric||m3m||Ia3d|
|Katoite||Ca3Al2(SiO4)(3-x)(OH)4x (x= 1.5-3)||isometric||m3m||Ia3d|
The crystallographic structure of garnets has been expanded from the prototype to include chemicals with the general formula A3B2(C O4)3. Besides silicon, a large number of elements have been put on the C site, including Ge, Ga, Al, V and Fe.
Yttrium aluminium garnet (YAG), Y3Al2(AlO4)3, is used for synthetic gemstones. Due to its fairly high refractive index, YAG was used as a diamond simulant in the 1970s until the methods of producing the more advanced simulant cubic zirconia in commercial quantities were developed. When doped with neodymium (Nd3+), these YAl-garnets may be used as the lasing medium in lasers.
Interesting magnetic properties arise when the appropriate elements are used. In yttrium iron garnet (YIG), Y3Fe2(FeO4)3, the five iron(III) ions occupy two octahedral and three tetrahedral sites, with the yttrium(III) ions coordinated by eight oxygen ions in an irregular cube. The iron ions in the two coordination sites exhibit different spins, resulting in magnetic behavior. YIG is a ferrimagnetic material having a Curie temperature of 550 K.
Another example is gadolinium gallium garnet, Gd3Ga2(GaO4)3 which is synthesized for use as a substrate for liquid-phase epitaxy of magnetic garnet films for bubble memory and magneto-optical applications.
The Garnet group is a key mineral in interpreting the genesis of many igneous and metamorphic rocks via geothermobarometry. Diffusion of elements is relatively slow in garnet compared to rates in many other minerals, and garnets are also relatively resistant to alteration. Hence, individual garnets commonly preserve compositional zonations that are used to interpret the temperature-time histories of the rocks in which they grew. Garnet grains that lack compositional zonation commonly are interpreted as having been homogenized by diffusion, and the inferred homogenization also has implications for the temperature-time history of the host rock.
Garnets are also useful in defining metamorphic facies of rocks. For instance, eclogite can be defined as a rock of basalt composition, but mainly consisting of garnet and omphacite. Pyrope-rich garnet is restricted to relatively high-pressure metamorphic rocks, such as those in the lower crust and in the Earth's mantle. Peridotite may contain plagioclase, or aluminium-rich spinel, or pyrope-rich garnet, and the presence of each of the three minerals defines a pressure-temperature range in which the mineral could equilibrate with olivine plus pyroxene: the three are listed in order of increasing pressure for stability of the peridotite mineral assemblage. Hence, garnet peridotite must have been formed at great depth in the earth. Xenoliths of garnet peridotite have been carried up from depths of 100 km (62 mi) and greater by kimberlite, and garnets from such disaggegated xenoliths are used as a kimberlite indicator minerals in diamond prospecting. At depths of about 300 to 400 km (190 to 250 mi) and greater, a pyroxene component is dissolved in garnet, by the substitution of (Mg,Fe) plus Si for 2Al in the octahedral (Y) site in the garnet structure, creating unusually silica-rich garnets that have solid solution towards majorite. Such silica-rich garnets have been identified as inclusions within diamonds.
Red garnets were the most commonly used gemstones in the Late Antique Roman world, and the Migration Period art of the "barbarian" peoples who took over the territory of the Western Roman Empire. They were especially used inlaid in gold cells in the cloisonné technique, a style often just called garnet cloisonné, found from Anglo-Saxon England, as at Sutton Hoo, to the Black Sea.
Pure crystals of garnet are still used as gemstones. The gemstone varieties occur in shades of green, red, yellow, and orange. In the US it is known as the birthstone for January. It is the state mineral of Connecticut, New York's gemstone, and star garnet (garnet with rutile asterisms) is the state gemstone of Idaho.
Garnet sand is a good abrasive, and a common replacement for silica sand in sand blasting. Alluvial garnet grains which are rounder are more suitable for such blasting treatments. Mixed with very high pressure water, garnet is used to cut steel and other materials in water jets. For water jet cutting, garnet extracted from hard rock is suitable since it is more angular in form, therefore more efficient in cutting.
Garnet paper is favored by cabinetmakers for finishing bare wood.
Garnet sand is also used for water filtration media.
As an abrasive, garnet can be broadly divided into two categories; blasting grade and water jet grade. The garnet, as it is mined and collected, is crushed to finer grains; all pieces which are larger than 60 mesh (250 micrometers) are normally used for sand blasting. The pieces between 60 mesh (250 micrometers) and 200 mesh (74 micrometers) are normally used for water jet cutting. The remaining garnet pieces that are finer than 200 mesh (74 micrometers) are used for glass polishing and lapping. Regardless of the application, the larger grain sizes are used for faster work and the smaller ones are used for finer finishes.
There are different kinds of abrasive garnets which can be divided based on their origin. The largest source of abrasive garnet today is garnet-rich beach sand which is quite abundant on Indian and Australian coasts and the main producers today are Australia and India.
This material is particularly popular due to its consistent supplies, huge quantities and clean material. The common problems with this material are the presence of ilmenite and chloride compounds. Since the material has been naturally crushed and ground on the beaches for past centuries, the material is normally available in fine sizes only. Most of the garnet at the Tuticorin beach in south India is 80 mesh, and ranges from 56 mesh to 100 mesh size.
Rock garnet is perhaps the garnet type used for the longest period of time. This type of garnet is produced in America, China and western India. These crystals are crushed in mills and then purified by wind blowing, magnetic separation, sieving and, if required, washing. Being freshly crushed, this garnet has the sharpest edges and therefore performs far better than other kinds of garnet. Both the river and the beach garnet suffer from the tumbling effect of hundreds of thousands of years which rounds off the edges.
Garnet has been mined in western Rajasthan in northwestern India for the past 200 years, but mainly for the gemstone grade stones. Abrasive garnet was mainly mined as a secondary product while mining for gem garnets and was used as lapping and polishing media for the glass industries. The host rock of the garnet here is garnetiferous mica schist and the total percentage of garnet is not more than 7% to 10%, which makes the material extremely costly and non-economical to extract for non-gemstone applications.
New York has garnet as its state gemstone,, Connecticut has almandine garnet as its state gemstone, Idaho has star garnet as its state gemstone,  and Vermont has grossular garnet as its state gemstone.
The characters of the PlayStation role-playing game Final Fantasy IX. Filling four CD-ROMs, Final Fantasy IX featured a cast containing a variety of major and minor characters. Players could control a maximum of four characters for combat at once, with eight main playable characters in the party and a few other, temporary characters.Cry Baby (Garnet Mimms song)
"Cry Baby" is a song originally recorded by Garnet Mimms and the Enchanters, in 1963, and later covered by rock singer Janis Joplin. Bert Berns wrote the song with Jerry Ragovoy. Garnet Mimms and the Enchanters recorded it for the United Artists record label. It topped the R&B chart and went to #4 on the Billboard Hot 100 chart in 1963, and paved the way for soul hits by Aretha Franklin and Otis Redding later in the decade. The third verse was spoken by Mimms until the repeated refrain of the repeated song title.Garnet, California
Garnet is a census-designated place in Riverside County, California. Garnet sits at an elevation of 797 feet (243 m). The 2010 United States census reported Garnet's population was 7,543.Garnet Bailey
Garnet Edward "Ace" Bailey (June 13, 1948 – September 11, 2001) was a Canadian professional ice hockey player and scout who was a member of Stanley Cup and Memorial Cup winning teams. He died at the age of 53 while aboard United Airlines Flight 175, which crashed into the South Tower of the World Trade Center in New York City during the September 11 attacks.Garnet Bay
Garnet Bay is an arm of the Foxe Basin in the Qikiqtaaluk Region of Nunavut, Canada. It is located on the northern coast of Foxe Peninsula, in western Baffin Island. The closest community is Cape Dorset, situated 137 km (85 mi) to the south, while Nuwata, a former settlement, is situated to the west.Garnet Coleman
Garnet Fredrick Coleman (born September 8, 1961) is an American politician. Since 1991, he has been a member of the Texas House of Representatives for the 147th district, located entirely within Houston, Texas and Harris County.Garnet Crow
Garnet Crow (stylized as GARNET CROW) was a Japanese pop/rock band formed in 1999 and associated with the Giza Studio record label. Members include Yuri Nakamura, Hitoshi Okamoto, Nana Azuki, and Hirohito Furui, with Nakamura leading on vocals. Music produced by Garnet Crow has its roots in the Neo Acoustic genre, and representative works include "Flying", "Yume Mita Ato De", and "Spiral". Despite prolific early singles, the band neither performed live nor appeared on TV prior to 2002.
The mixed composition of Garnet Crow and Nakamura's deep vocals set the group apart from its contemporaries. Each individual member has also seen industry success: Nakamura and Azuki often share the limelight for Garnet Crow, but Okamoto has achieved a solo career and Furui is a sought-after music arranger – one of the highest paid in Japan.On March 30, 2013, the band announced their disbandment, with their final concert scheduled to be held on June 9, 2013. On June 9, 2013 they announced that they would break up during the final concert.Garnet Lake
Garnet Lake is located south of the hamlet of Garnet Lake, New York. Fish species present in the lake are pickerel, largemouth bass, yellow perch, and brown bullhead. There is carry down on a trail off Maxam Road on the east shore.Garnet Wolseley, 1st Viscount Wolseley
Field Marshal Garnet Joseph Wolseley, 1st Viscount Wolseley (4 June 1833 – 25 March 1913), was an Anglo-Irish officer in the British Army. He became one of the most influential and admired British generals after a series of successes in Canada, West Africa, and Egypt, followed by a central role in modernizing the British Army in promoting efficiency. He served in Burma, the Crimean War, the Indian Mutiny, China, Canada and widely throughout Africa—including his Ashanti campaign (1873–1874) and the Nile Expedition against Mahdist Sudan in 1884–85. Wolseley served as Commander-in-Chief of the Forces from 1895 to 1900. His reputation for efficiency led to the late 19th century English phrase "everything's all Sir Garnet", meaning, "All is in order."Gore Mountain (New York)
Gore Mountain is a mountain located near the village of North Creek in Warren County, New York, of which its peak is the highest point.
Gore is flanked to the north by South Mountain, and to the southwest by Height of Land Mountain.
The mountain is the site of the popular Gore Mountain ski resort.Grossular
Grossular is a calcium-aluminium species of the garnet group of minerals. It has the chemical formula of Ca3Al2(SiO4)3 but the calcium may, in part, be replaced by ferrous iron and the aluminium by ferric iron. The name grossular is derived from the botanical name for the gooseberry, grossularia, in reference to the green garnet of this composition that is found in Siberia. Other shades include cinnamon brown (cinnamon stone variety), red, and yellow. Grossular is a gemstone.
its streak is brownish white
In geological literature, grossular has often been called grossularite. Since 1971, however, use of the term grossularite for the mineral has been discouraged by the International Mineralogical Association.Gunpowder Plot
The Gunpowder Plot of 1605, in earlier centuries often called the Gunpowder Treason Plot or the Jesuit Treason, was a failed assassination attempt against King James I by a group of provincial English Catholics led by Robert Catesby.
The plan was to blow up the House of Lords during the State Opening of Parliament on 5 November 1605, as the prelude to a popular revolt in the Midlands during which James's nine-year-old daughter, Elizabeth, was to be installed as the Catholic head of state. Catesby may have embarked on the scheme after hopes of securing greater religious tolerance under King James had faded, leaving many English Catholics disappointed. His fellow plotters were John and Christopher Wright, Robert and Thomas Wintour, Thomas Percy, Guy Fawkes, Robert Keyes, Thomas Bates, John Grant, Ambrose Rookwood, Sir Everard Digby and Francis Tresham. Fawkes, who had 10 years of military experience fighting in the Spanish Netherlands in the failed suppression of the Dutch Revolt, was given charge of the explosives.
The plot was revealed to the authorities in an anonymous letter sent to William Parker, 4th Baron Monteagle, on 26 October 1605. During a search of the House of Lords at about midnight on 4 November 1605, Fawkes was discovered guarding 36 barrels of gunpowder—enough to reduce the House of Lords to rubble—and arrested. Most of the conspirators fled from London as they learned of the plot's discovery, trying to enlist support along the way. Several made a stand against the pursuing Sheriff of Worcester and his men at Holbeche House; in the ensuing battle, Catesby was one of those shot and killed. At their trial on 27 January 1606, eight of the survivors, including Fawkes, were convicted and sentenced to be hanged, drawn and quartered.
Details of the assassination attempt were allegedly known by the principal Jesuit of England, Father Henry Garnet. Although he was convicted of treason and sentenced to death, doubt has been cast on how much he really knew of the plot. As its existence was revealed to him through confession, Garnet was prevented from informing the authorities by the absolute confidentiality of the confessional. Although anti-Catholic legislation was introduced soon after the plot's discovery, many important and loyal Catholics retained high office during King James I's reign. The thwarting of the Gunpowder Plot was commemorated for many years afterwards by special sermons and other public events such as the ringing of church bells, which have evolved into the Bonfire Night of today.Mu Cephei
Mu Cephei (μ Cep, μ Cephei), also known as Herschel's Garnet Star, is a red supergiant or hypergiant star in the constellation Cepheus. It appears garnet red and is located at the edge of the IC 1396 nebula. Since 1943, the spectrum of this star has served as the M2 Ia standard by which other stars are classified.Mu Cephei is visually nearly 100,000 times brighter than the Sun, with an absolute visual magnitude of −7.6. It is also one of the largest known stars with an estimated radius over 1,000 times that of the sun (R☉), and were it placed in the Sun's position it would reach between the orbit of Jupiter and Saturn.Nashville Garnet and Blue football
The Nashville Garnet and Blue football team represented the University of Nashville in intercollegiate football competition. The program was active from 1889 until 1909, when it was discontinued. In 1890, the school challenged local Vanderbilt to a game, leading to the first intercollegiate game in Tennessee.
John Heisman, whose Auburn team defeated Nashville 14–4 in 1897, said Bradley Walker was the best ever to play for the Nashville football team.The 1901 team, coached by Charley Moran was one of the South's first great teams. In 1903, E. A. Wreidt, the team's coach, resigned and Nashville football was threatened with its end, but it survived for a few more years.Palm OS
Palm OS (also known as Garnet OS) is a discontinued mobile operating system initially developed by Palm, Inc., for personal digital assistants (PDAs) in 1996. Palm OS was designed for ease of use with a touchscreen-based graphical user interface. It is provided with a suite of basic applications for personal information management. Later versions of the OS have been extended to support smartphones. Several other licensees have manufactured devices powered by Palm OS.
Following Palm's purchase of the Palm trademark, the currently licensed version from ACCESS was renamed Garnet OS. In 2007, ACCESS introduced the successor to Garnet OS, called Access Linux Platform and in 2009, the main licensee of Palm OS, Palm, Inc., switched from Palm OS to webOS for their forthcoming devices.Pike County, Ohio
Pike County is a county located in the Appalachian region of the U.S. state of Ohio. As of the 2010 census, the population was 28,709. Its county seat is Waverly. The county is named for explorer Zebulon Pike.Swarthmore College
Swarthmore College (, locally [swɑθ-]) is a private liberal arts college in Swarthmore, Pennsylvania. Founded in 1864, Swarthmore was one of the earliest coeducational colleges in the United States. It was established to be a college "...under the care of Friends, at which an education may be obtained equal to that of the best institutions of learning in our country." By 1906, Swarthmore had dropped its religious affiliation and became officially non-sectarian.Swarthmore is a member of the Tri-College Consortium along with Bryn Mawr and Haverford College, a cooperative academic arrangement between the three schools. Swarthmore is also affiliated with the University of Pennsylvania through the Quaker Consortium, which allows for students to cross-register for classes at all four institutions. Swarthmore offers over 600 courses a year in more than 40 areas of study, including an ABET accredited engineering program which culminates with a Bachelor of Science in engineering. Swarthmore has a variety of sporting teams with a total of 22 Division III Varsity Intercollegiate Sports Teams and competes in the Centennial Conference, a group of private colleges in Pennsylvania and Maryland.Despite the school's small size, Swarthmore alumni have attained prominence in a broad range of fields. Graduates include five Nobel Prize winners (as of 2016, the third-highest number of Nobel Prize winners per graduate in the U.S.), 11 MacArthur Foundation fellows, 30 Rhodes Scholars, 27 Truman Scholars, 10 Marshall Scholars, 201 Fulbright Grantees, and many noteworthy figures in law, art, science, academia, business, politics, and other fields. Swarthmore also counts 49 alumni as members of the National Academies of Science, Engineering and Medicine.
Swarthmore is currently ranked 3rd best liberal arts college in the country by U.S. News and World Report.Swarthmore Garnet Tide football
The Swarthmore Garnet Tide represented Swarthmore College in the sport of college football.Yttrium aluminium garnet
Yttrium aluminium garnet (YAG, Y3Al5O12) is a synthetic crystalline material of the garnet group. It is also one of three phases of the yttrium-aluminium composite, the other two being yttrium aluminium monoclinic (YAM, Y4Al2O9) and yttrium aluminium perovskite (YAP, YAlO3).YAG, like garnet and sapphire, has no uses as a laser medium when pure. However, after being doped with an appropriate ion, YAG is commonly used as a host material in various solid-state lasers. Rare earth elements such as neodymium and erbium can be doped into YAG as active laser ions, yielding Nd:YAG and Er:YAG lasers, respectively. Cerium-doped YAG (Ce:YAG) is used as a phosphor in cathode ray tubes and white light-emitting diodes, and as a scintillator.