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Chemical Composition : (Mg,Fe2+)4Al6(Si,Al,B)5O21(OH) Magnesium Iron Aluminum Boro-silicate Hydroxide
Hardness : 6.0 – 7.0Moh
Specific Gravity (Density) : 3.28 – 3.35 (g/cm3)
Refractive Index : 1.660 – 1.684 Biaxial ( – ); may be pseudouniaxial ( – )
Kornerupine is a rare gemstone that is available in shades of green, bluish green, yellowish green and yellowish brown. The most desirable gems are the emerald green gems from Sri Lanka and Tanzania that are colored green by the presence of vanadium. Beautiful bluish green Kornerupine gems come from Madagascar and cats eye cabochons are available from Sri Lanka. Star Kornerupine has been found in Mogok, Myanmar (Burma) but is very rare. Kornerupine was originally found in Greenland as non-gemmy, radiating crystals but later found there as dark green gemmy crystals.
Kornerupine was named in 1884 by Danish mineralogist Johannes Theodor Lorenzen (1855-1884) in honor of Danish geologist, Andreas Nikolaus Kornerup (1857-1883). Kornerup died at age 26 from a lung disease he contracted while on an expedition in Greenland. Although Kornerup died at such a young age, he managed to establish himself as a well respected geologist in Greenland research. Coincidentally, Johannes Lorenzen also died at a young age, 29, while on an expedition in Greenland in 1884.
Current sources of gem quality crystals are Ivohibe District, Horombe Region, Fianarantsoa Province, Madagascar; Mogok Township, Pyin-Oo-Lwin District, Mandalay Division, Burma (Myanmar); Matara District, Southern Province, Sri Lanka; Lelatema Mts, Simanjiro District, Manyara Region, Tanzania.
Kornerupine distribution: some localities for well-studied material: In Greenland, at Fiskenæsset. At Bjordam, near Kragerö, Norway. In Germany, from Waldheim, Saxony. From Mautia Hill, Tanzania. On the Bok se Puts Farm, Namaqualand, Cape Province, South Africa. Gem crystals from Itrongahy, near Betroka, and elsewhere in Madagascar. From gem gravels of the Matale, Ratnapura, and Embilipitiya districts, Sri Lanka. In the Harts and Strangways Ranges, Northern Territory, Australia. At Lac Ste-Marie, Quebec, Canada.