![]() Chemically, almandine is an iron-aluminium garnet with the formula Fe 3Al 2(SiO 4) 3 the deep red transparent stones are often called precious garnet and are used as gemstones (being the most common of the gem garnets). The name Almandine is a corruption of Alabanda, a region in Asia Minor where these stones were cut in ancient times. ![]() ![]() The term "carbuncle" is derived from the Latin meaning "live coal" or burning charcoal. Garnet group end member species Pyralspite garnets – aluminium in Y site Īlmandine, sometimes incorrectly called almandite, is the modern gem known as carbuncle (though originally almost any red gemstone was known by this name). 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. Magnetics used in garnet series identification įor 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. The harder species like almandine are often used for abrasive purposes. As a result, this mineral group shows a range of hardness on the Mohs scale of about 6.0 to 7.5. Silicon ion size exaggerated to emphasize silica tetrahedraīecause the chemical composition of garnet varies, the atomic bonds in some species are stronger than in others. Garnets do not have any cleavage planes, so when they fracture under stress, sharp, irregular ( conchoidal) pieces are formed. GarnetĤ / m 3 ¯ 2 / m families of planes are depleted. For other uses, see Garnet (disambiguation).
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