Garnet is a group of minerals that have been used since the Bronze Age as gemstones and abrasives. Today, it is widely known as the birthstone for January. It's often seen in red, but are available in a wide variety of colors spanning the entire spectrum. The name "garnet" may have been inherited from the Latingranatus ("grain"), possibly a reference to "pomegranate", a plant with red seeds similar in shape, size, and color to some garnet crystals.
Six common varieties of garnet are recognized based on their chemical composition. They are pyrope, almandine, spessartite, grossular, uvarovite and andradite.
Appearance
Garnets are found in many colors including red, orange, yellow, green, blue, purple, brown, black, and colorless. The rarest of these is the blue garnet, was discovered in the late 1990s in Bekily, Madagascar. It is also found in some parts of the United States and Russia. They usually show up with their colors ranging from shades of green, beige, brown, gray, and blue in day light and appear reddish or purplish/pink color in incandescent light. Because of their color changing quality, this kind of garnet is often mistaken for Alexandrite.
Crystal Structure
Garnets are nesosilicates having the general formula X 3Y 2(SiO 4) 3. Garnets are often found in the dodecahedralcrystal habit, but are also commonly found in the trapezohedron habit. They crystallize in the isometric system, having three axes that are all of equal length and perpendicular to each other. Garnets do not show cleavage, so when it is put under stress, sharp irregular pieces are formed.
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