Kornerupine
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Kornerupine (also called ''Prismatine'') is a rare
boro __NOTOC__ Boro may refer to: People * Boro people, indigenous peoples of Amazonas, Brazil * A variant spelling for the Bodo people of northeast India * Charan Boro, Indian politician * Isaac Adaka Boro, a celebrated Niger Delta nationalist and Nig ...
-
silicate mineral Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, silica (silicon dioxide, ) is usually consid ...
with the chemical formula . It crystallizes in the orthorhombic - dipyramidal
crystal system In crystallography, a crystal system is a set of point groups (a group of geometric symmetries with at least one fixed point). A lattice system is a set of Bravais lattices. Space groups are classified into crystal systems according to their poin ...
as brown, green, yellow to colorless slender tourmaline like prisms or in massive fibrous forms. It has a
Mohs hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by t ...
of 7 and a
specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water at its densest ...
of 3.3 to 3.34. Its indices of refraction are nα=1.660 - 1.671, nβ=1.673 - 1.683 and nγ=1.674 - 1.684. It occurs in boron-rich
volcanic A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates a ...
and sedimentary rocks which have undergone high grade
metamorphism Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of ch ...
. It is also found in metamorphosed
anorthosite Anorthosite () is a phaneritic, intrusive igneous rock characterized by its composition: mostly plagioclase feldspar (90–100%), with a minimal mafic component (0–10%). Pyroxene, ilmenite, magnetite, and olivine are the mafic minerals most ...
complexes. Kornerupine is valued as a gemstone when it is found in translucent green to yellow shades. The emerald green varieties are especially sought after. It forms a solid solution series with prismatine. Strongly
pleochroic Pleochroism (from Greek πλέων, ''pléōn'', "more" and χρῶμα, ''khrôma'', "color") is an optical phenomenon in which a substance has different colors when observed at different angles, especially with polarized light. Backgroun ...
, it appears green or reddish brown when viewed from different directions. It has a vitreous luster. It was first described in 1884 for an occurrence in Fiskernæs in southwest
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland i ...
. It was named in honor of the Danish geologist, Andreas Nikolaus Kornerup (1857–1883). Although kornerupine was named in 1884, it was not until 1912 that gem-quality material was found and it remains uncommon to this day. Deposits are found in
Burma Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John Wells explai ...
(
Myanmar Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John Wells explai ...
),
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(
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),
Kenya ) , national_anthem = " Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi ...
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, Sri Lanka,
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, and
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.


References

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Mineral galleries
Sorosilicates Orthorhombic minerals Minerals in space group 63 Gemstones