Difference between revisions of "Chrysoberyl"
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[[File:Chrysoberyl Raman RRUFF R0110103.png|thumb|Raman spectrum of Chrysoberyl from [https://rruff.info/alexandrite/display=default/R110103 RRUFF]]] | [[File:Chrysoberyl Raman RRUFF R0110103.png|thumb|Raman spectrum of Chrysoberyl from [https://rruff.info/alexandrite/display=default/R110103 RRUFF]]] | ||
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==Physical and Chemical Properties== | ==Physical and Chemical Properties== | ||
| − | * Orthorhombic crystal system | + | * Orthorhombic crystal system with tabular or short prismatic crystals |
| − | * Good cleavage in one direction | + | * Good cleavage in one direction |
| − | * Fracture = uneven to conchoidal | + | * Fracture = uneven to conchoidal |
| − | * Luster = vitreous | + | * Luster = vitreous |
| − | * Streak = colorless to white | + | * Streak = colorless to white |
| − | * Alexandrite is strongly pleochroic | + | * Fluorescence = generally inert; yellow to green stone may show weak yellow under SW; 'mint' chrysoberyl shows strong red in LW |
| + | * Pleochroism = generally weak to moderate (red, yellow, green); Alexandrite is strongly pleochroic (green, red) | ||
{| class="wikitable" | {| class="wikitable" | ||
| Line 32: | Line 32: | ||
! scope="row"| Refractive Index | ! scope="row"| Refractive Index | ||
| 1.745-1.754 | | 1.745-1.754 | ||
| + | |- | ||
| + | ! scope="row"| Birefringence | ||
| + | | 0.008 - 0.010 | ||
|} | |} | ||
| Line 41: | Line 44: | ||
* Mineralogy Database: [http://www.webmineral.com/data/Chrysoberyl.shtml Chrysoberyl] | * Mineralogy Database: [http://www.webmineral.com/data/Chrysoberyl.shtml Chrysoberyl] | ||
* Jack Odgen, ''Jewellery of the Ancient World'', Rizzoli International Publications Inc., New York City, 1982 | * Jack Odgen, ''Jewellery of the Ancient World'', Rizzoli International Publications Inc., New York City, 1982 | ||
| − | + | * Gem Identification Lab Manual, Gemological Institute of America, 2016. | |
* R.F.Symmes, T.T.Harding, Paul Taylor, ''Rocks, Fossils and Gems'', DK Publishing, Inc., New York City, 1997 | * R.F.Symmes, T.T.Harding, Paul Taylor, ''Rocks, Fossils and Gems'', DK Publishing, Inc., New York City, 1997 | ||
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* ''Encyclopedia Britannica'', http://www.britannica.com Comment: "chrysoberyl." Accessed 7 Apr. 2005 . | * ''Encyclopedia Britannica'', http://www.britannica.com Comment: "chrysoberyl." Accessed 7 Apr. 2005 . | ||
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* C.W.Chesterman, K.E.Lowe, ''Audubon Society Field Guide to North American Rocks and Minerals'', Alfred A. Knopf, New York, 1979 | * C.W.Chesterman, K.E.Lowe, ''Audubon Society Field Guide to North American Rocks and Minerals'', Alfred A. Knopf, New York, 1979 | ||
| − | + | * Wikipedia: [https://en.wikipedia.org/wiki/Chrysoberyl#Alexandrite Chrysoberyl] (Accessed Sept. 2, 2005 and Dec 2022) | |
| − | * Wikipedia: | ||
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* G.S.Brady, ''Materials Handbook'', McGraw-Hill Book Co., New York, 1971 Comment: p. 101 | * G.S.Brady, ''Materials Handbook'', McGraw-Hill Book Co., New York, 1971 Comment: p. 101 | ||
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* ''Van Nostrand's Scientific Encyclopedia'', Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976 | * ''Van Nostrand's Scientific Encyclopedia'', Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976 | ||
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* Random House, ''Webster's Encyclopedic Unabridged Dictionary of the English Language'', Grammercy Book, New York, 1997 | * Random House, ''Webster's Encyclopedic Unabridged Dictionary of the English Language'', Grammercy Book, New York, 1997 | ||
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* ''The American Heritage Dictionary'' or ''Encarta'', via Microsoft Bookshelf 98, Microsoft Corp., 1998 | * ''The American Heritage Dictionary'' or ''Encarta'', via Microsoft Bookshelf 98, Microsoft Corp., 1998 | ||
Latest revision as of 11:59, 23 December 2022
Description
A hard green to yellow mineral composed of beryllium aluminate. Chrysoberyl occurs in granitic rocks, pegmatites, and mica schists. Some transparent varieties of chrysoberyl have been used as gemstones. In the 18th century, a large deposit of clear, yellowish-green chrysoberyls was found in Brazil and the stones were popularly used for Portuguese and Spanish jewelry. Cat's eye chrysoberyls are cut as cabochons and polished. The Alexandrite variety of chrysoberyl appears red in artificial light and green in daylight. Chrysoberyls are found in the Ural Mountains (alexandrite), Czech Republic, Sri Lanka, Rhodesia, Brazil, Malagasy Republic and the United States (New York, Colorado).
Synonyms and Related Terms
cat's eye; cymophane; golden beryl; alexandrite; oriental chrysolite; crisoberilo (Esp., Port.); chryzoberyl (Pol.); Chrysoberyll (Deut.); chrysoberyl (Ned.)
Raman spectrum of Chrysoberyl from RRUFF
Physical and Chemical Properties
- Orthorhombic crystal system with tabular or short prismatic crystals
- Good cleavage in one direction
- Fracture = uneven to conchoidal
- Luster = vitreous
- Streak = colorless to white
- Fluorescence = generally inert; yellow to green stone may show weak yellow under SW; 'mint' chrysoberyl shows strong red in LW
- Pleochroism = generally weak to moderate (red, yellow, green); Alexandrite is strongly pleochroic (green, red)
| Composition | BeAl2O4 |
|---|---|
| Mohs Hardness | 8.5 |
| Density | 3.5-3.8 g/ml |
| Refractive Index | 1.745-1.754 |
| Birefringence | 0.008 - 0.010 |
Comparisons
Resources and Citations
- Mineralogy Database: Chrysoberyl
- Jack Odgen, Jewellery of the Ancient World, Rizzoli International Publications Inc., New York City, 1982
- Gem Identification Lab Manual, Gemological Institute of America, 2016.
- R.F.Symmes, T.T.Harding, Paul Taylor, Rocks, Fossils and Gems, DK Publishing, Inc., New York City, 1997
- Encyclopedia Britannica, http://www.britannica.com Comment: "chrysoberyl." Accessed 7 Apr. 2005 .
- C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
- Wikipedia: Chrysoberyl (Accessed Sept. 2, 2005 and Dec 2022)
- G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 101
- Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
- Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
- The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998