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Chemical Composition : Fe2+3Al2(SiO4)3 Iron Aluminum Silicate
Hardness : 7.0 – 7.5
Specific Gravity (Density) : 4.318 (g/cm3)
Refractive Index : 1.830 Isotropic
Almandine is a member of the Garnet Group of minerals that includes Almandine, Andradite, Grossular, Pyrope, Spessartine and Uvarovite. Almandine is the most common variety of Garnet. Almandine always contain some Spessartine and Pyrope components which creates a wide range of colors including brown, red-brown, purplish red, wine red, purple and deep red. Almandine is the iron aluminum garnet. Pure Almandine and pure Pyrope are rare in nature and most specimens are a percentage of the two. Silky inclusions may be present in many Almandine gems that is only visible under magnification. However, material from Idaho, USA and India is known to contain inclusions of asbestiform minerals such as pyroxene and amphibole which create a chatoyancy that produces a 4-rayed star.
Almandine, like other varieties of Garnet, forms rounded crystals with 12 rhombic or 24 trapezoidal faces or combinations of these and some other forms. This crystal habit is classic for the Garnet Group of minerals.
Distribution: Widespread. Some localities for fine crystals include: in the Zillertal, Tirol, Austria. At Falun, Sweden. In Norway, from near Bod¿. From the Akhmatovsk deposit, near Zlatoust, Ural Mountains, Russia. In the USA, from Roxbury, Litchfield County, and Southbury, New Haven County, Connecticut; at Auburn, Androscoggin County, and Topsham, Sagadahoc County, Maine; from Westfield and Russell, Hampden County, Massachusetts; and at Hanover, Grafton County, New Hampshire. From Avondale, Chester County, Pennsylvania; a large commercial deposit at the Barton mine, North Creek, Warren County, New York; at Michigamme, Marquette County, Michigan; from Salida, Chaffee County, Colorado; and at Ft. Wrangell, Stikine River, Alaska. In Brazil, at Pernambuco, Bahia. From the Miami district, Zimbabwe. At Broken Hill and Thackaringa, New South Wales, and in the Harts Range, Northern Territory, Australia. From Yamanoo, Ibaragi Prefecture, and the Ishikawa district, Fukushima Prefecture, Japan.