Garnet facts for kids
Quick facts for kids Garnet |
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| General | |
| Category | Nesosilicate |
| Formula (repeating unit) |
The general formula X3Y2(SiO4)3 |
| Identification | |
| Color | virtually all colors, blue very rare |
| Crystal habit | Rhombic dodecahedron or cubic |
| Cleavage | Indistinct |
| Fracture | conchoidal to uneven |
| Mohs scale hardness | 6.5–7.5 |
| Luster | vitreous to resinous |
| Streak | White |
| Specific gravity | 3.1–4.3 |
| Polish luster | vitreous to subadamantine |
| Optical properties | Single refractive, often anomalous double refractive |
| Refractive index | 1.72–1.94 |
| Birefringence | None |
| Pleochroism | None |
| Ultraviolet fluorescence | variable |
| Other characteristics | variable magnetic attraction |
| Major varieties | |
| Pyrope | Mg3Al2Si3O12 |
| Almandine | Fe3Al2Si3O12 |
| Spessartine | Mn3Al2Si3O12 |
| Andradite | Ca3Fe2Si3O12 |
| Grossular | Ca3Al2Si3O12 |
| Uvarovite | Ca3Cr2Si3O12 |
A garnet is one kind of silicate mineral. There are many different kinds of garnets, containing different metals. Crystals of garnet are often large and pretty. Their most common color is red or purple, but they can be found in almost all colors and are often used in jewelry. Garnet is the birthstone for people born in the month of January.
Related pages
Images for kids
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A sample showing the deep red color garnet can exhibit.
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Crystal structure model of garnet
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End member compositions of the garnet mineral group.
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Red Garnet
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Almandine in metamorphic rock
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Spessartine (the reddish mineral)
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Grossular garnet from Quebec, collected by Dr John Hunter in the 18th century, Hunterian Museum, Glasgow
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Grossular on display at the U.S. National Museum of Natural History. The green gem at right is a type of grossular known as tsavorite.
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Main garnet producing countries
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Garnet var. Spessartine, Putian City, Putian Prefecture, Fujian Province, China
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c. 8th century AD, Anglo-Saxon sword hilt fitting – gold with gemstone inlay of garnet cloisonné. From the Staffordshire Hoard, found in 2009, and not fully cleaned.
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Pendant in uvarovite, a rare bright-green garnet.
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Crystal structure of pyrope garnet. White spheres are oxygen; black, silicon; blue, aluminium; and red, magnesium.
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Same view, with ion sizes reduced to better show all ions
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Silicon ion size exaggerated to emphasize silica tetraheda
See also
In Spanish: Granate (mineral) para niños
