Difference between revisions of "Jadeite" - New World Encyclopedia

From New World Encyclopedia
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:''This article is about the mineral named jadeite. For the Sailor Moon character, see [[Shitennou (Sailor Moon)|Shitennou]].''
 
 
 
{{Infobox mineral
 
{{Infobox mineral
 
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| name        = Jadeite
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'''Jadeite''' is a [[pyroxene]] mineral with composition NaAlSi<sub>2</sub>O<sub>6</sub>. It is [[monoclinic]]. It has a Mohs hardness of about 6.5 to 7.0 depending on the composition. The mineral is dense, with a specific gravity of about 3.4. Jadeitite forms solid solutions with other pyroxene endmembers such as [[augite]] and [[diopside]] (CaMg-rich endmembers), [[aegirine]] (NaFe endmember), and [[kosmochlor]] (NaCr endmember). Pyroxenes rich in both the jadeite and augite endmembers are known as [[omphacite]].
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'''Jadeite''' is a [[pyroxene]] mineral with composition NaAlSi<sub>2</sub>O<sub>6</sub>.
 +
It is one of the minerals recognized as the gemstone [[jade]].<ref>The other mineral recognized as "jade" is [[nephrite]], a green [[amphibole]].</ref>
 +
 
 +
== Characteristics ==
 +
 
 +
Jadeite is [[monoclinic]]. It has a Mohs hardness of about 6.5 to 7.0 depending on the composition. The mineral is dense, with a specific gravity of about 3.4. Jadeitite forms solid solutions with other pyroxene endmembers such as [[augite]] and [[diopside]] (CaMg-rich endmembers), [[aegirine]] (NaFe endmember), and [[kosmochlor]] (NaCr endmember). Pyroxenes rich in both the jadeite and augite endmembers are known as [[omphacite]].
  
Jadeite is formed in [[metamorphic rock]]s under high pressure and relatively low temperature conditions. [[Albite]] (NaAlSi<sub>3</sub>O<sub>8</sub>) is a common mineral of the Earth's crust, and it has a specific gravity of about 2.6, much less than that of jadeite. With increasing pressure, albite breaks down to form the high-pressure assemblage of jadeite plus [[quartz]]. Minerals associated with jadeite include: [[glaucophane]], [[lawsonite]], [[muscovite]], [[aragonite]], [[serpentine]], and [[quartz]].  
+
Jadeite's color commonly ranges from white through pale apple green to deep [[jade (color)|jade'' green]] but can also be blue-green (like the famous and recently rediscovered "Olmec Blue" jade), pink, lavender, and a multitude of other rare colors.  Color is largely affected by the presence of trace elements such as chromium and iron.  Its translucence can be anywhere from entirely solid through opaque to almost clear.  Variations in color and translucence are often found even within a single specimen.  Currently, the best known sources of gem quality jadeite are [[California]], [[Myanmar]], [[New Zealand]] and more recently [[Guatemala]]; other localities of jadeite include [[Kazakhstan]], [[Russia]], [[British Columbia]], [[Alaska]], and [[Turkestan]].
 +
 
 +
== Formation ==
 +
 
 +
Jadeite is formed in [[metamorphic rock]]s under high pressure and relatively low temperature conditions. [[Albite]] (NaAlSi<sub>3</sub>O<sub>8</sub>) is a common mineral of the Earth's crust, and it has a specific gravity of about 2.6, much less than that of jadeite. With increasing pressure, albite breaks down to form the high-pressure assemblage of jadeite plus [[quartz]]. Minerals associated with jadeite include: [[glaucophane]], [[lawsonite]], [[muscovite]], [[aragonite]], [[serpentine]], and quartz.  
  
 
Rocks that consist almost entirely of jadeite are called [[jadeitite]]. In all well-documented occurrences, jadeitite appears to have formed from [[subduction zone]] fluids in association with [[serpentinite]], as discussed by Sorensen et al. (2006). Jadeitite is resistant to weathering, and boulders of jadeitite released from the serpentine-rich environments in which they formed are found in a variety of environments.  
 
Rocks that consist almost entirely of jadeite are called [[jadeitite]]. In all well-documented occurrences, jadeitite appears to have formed from [[subduction zone]] fluids in association with [[serpentinite]], as discussed by Sorensen et al. (2006). Jadeitite is resistant to weathering, and boulders of jadeitite released from the serpentine-rich environments in which they formed are found in a variety of environments.  
  
Jadeite's color commonly ranges from white through pale apple green to deep [[jade (color)|jade'' green]] but can also be blue-green (like the famous and recently rediscovered "Olmec Blue" jade), pink, lavender, and a multitude of other rare colors.  Color is largely affected by the presence of trace elements such as chromium and iron.  Its translucence can be anywhere from entirely solid through opaque to almost clear.  Variations in color and translucence are often found even within a single specimen.  Currently, the best known sources of gem quality jadeite are [[California]], [[Myanmar]], [[New Zealand]] and more recently [[Guatemala]]; other localities of jadeite include [[Kazakhstan]], [[Russia]], [[British Columbia]], [[Alaska]], and [[Turkestan]].
+
== Varieties and value ==
 
+
 
Jadeite is one of the minerals recognized as the gemstone [[jade]]. The other is the green [[amphibole]], [[nephrite]]. Jadeite from the Motagua Valley, [[Guatemala]] is the stone used by the [[Olmec]], [[Maya peoples]], and the indigenous peoples of [[Costa Rica]]. Typically, the most highly valued colors of jadeite are the most intensely green, translucent varieties, though traditionally white has been considered the most valuable of the jades by the Chinese, known for their carefully crafted jade pieces. Currently, the most highly valued variety of jadeite is known as "Imperial Green" jade and is characterized by an emerald green color with a high level of translucence. It the most expensive gem in the world, carat-by-carat costing more than diamond. Other colors, like "Olmec Blue" jade, which is characterized by its deep blue-green, translucent hue with white flecking, are also becoming more highly valued because of its unique beauty and historical use by the Mesoamerican [[Olmec]] and also in [[Costa Rica]]<ref>Easby, Elizabeth Kennedy. ''Pre-Columbian Jade from Costa Rica''. (1968). André Emmerich Inc., New York</ref> ; however, this variety was only recently rediscovered and is only being minimally exploited by native Guatemalans. It is thus difficult to obtain and as yet too rare and little known to have attained great value as a gemstone. When purchasing jade, quality is determined by the degree of translucence, cleanness of color, and purity of color. Occasionally, other minerals like [[serpentine]] or [[quartz]] are sold as jade but the difference can be determined by cleavage and hardness.
+
Jadeite from the Motagua Valley, [[Guatemala]] is the stone used by the [[Olmec]], [[Maya peoples]], and the indigenous peoples of [[Costa Rica]]. Typically, the most highly valued colors of jadeite are the most intensely green, translucent varieties, though traditionally white has been considered the most valuable of the jades by the Chinese, known for their carefully crafted jade pieces.
 +
 
 +
Currently, the most highly valued variety of jadeite is known as "Imperial Green" jade, characterized by an emerald green color and a high level of translucence. It the most expensive gem in the world, carat-by-carat, costing more than diamond. "Olmec blue" jade, characterized by its deep blue-green, translucent hue with white flecking, is also becoming more highly valued because of its unique beauty and historical use by the Mesoamerican [[Olmec]] and the peoples of [[Costa Rica]].<ref>Elizabeth Kennedy Easby, ''Pre-Columbian Jade from Costa Rica'' (New York: André Emmerich, 1968).</ref> The Olmec blue variety, however, was only recently rediscovered and is being minimally exploited by native Guatemalans. It is thus difficult to obtain and too rare and little-known to have attained great value as a gemstone.
 +
 
 +
When purchasing jade, quality is determined by the degree of translucence, cleanness of color, and purity of color. Occasionally, other minerals like [[serpentine]] or [[quartz]] are sold as jade but the difference can be determined by cleavage and hardness.
 +
 
 +
== See also ==
 +
 
 +
* [[Amphibole]]
 +
* [[Jade]]
 +
* [[Mineral]]
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* [[Pyroxene]]
  
 
== Notes ==
 
== Notes ==
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* Sorensen, Sorena, George E. Harlow, and Douglas Rumble. 2006. The origin of jadeitite-forming subduction-zone fluids: CL-guided SIMS oxygen-isotope  and trace-element evidence. ''American Mineralogist'' 91:979-96.
 
* Sorensen, Sorena, George E. Harlow, and Douglas Rumble. 2006. The origin of jadeitite-forming subduction-zone fluids: CL-guided SIMS oxygen-isotope  and trace-element evidence. ''American Mineralogist'' 91:979-96.
 +
 +
== External links ==
 +
 +
* Mindat.org. 2007. [http://www.mindat.org/min-2062.html Jadeite.] ''Mindat.org''. Retrieved March 24, 2007.
  
 
[[Category:Physical sciences]]
 
[[Category:Physical sciences]]

Revision as of 00:34, 27 March 2007

Jadeite
Chinese jadeite buttons.jpg
A selection of antique, hand-crafted Chinese jadeite buttons
General
Categorymineral variety of pyroxene
Chemical formulaNaAlSi2O6[1]
Identification
ColorSemitransparent to opaque and often mottled, white, green, yellow to reddish orange, brown, gray, black, light purple or lavender.[1]
Crystal habitmassive[1]
Crystal systemmonoclinic[1]
Fracturegranular to splintery[1]
Mohs Scale hardness6.5 - 7[1]
Lusterdull[1]
Refractive index1.666 - 1.680 (+/- .008); spot reading is 1.66[1]
Optical PropertiesDouble refractive with anomalous aggregate reaction [1]
Birefringenceusually not detectable[1]
Pleochroismnone[1]
Specific gravity3.34 (+.06, -.09)

Jadeite is a pyroxene mineral with composition NaAlSi2O6. It is one of the minerals recognized as the gemstone jade.[2]

Characteristics

Jadeite is monoclinic. It has a Mohs hardness of about 6.5 to 7.0 depending on the composition. The mineral is dense, with a specific gravity of about 3.4. Jadeitite forms solid solutions with other pyroxene endmembers such as augite and diopside (CaMg-rich endmembers), aegirine (NaFe endmember), and kosmochlor (NaCr endmember). Pyroxenes rich in both the jadeite and augite endmembers are known as omphacite.

Jadeite's color commonly ranges from white through pale apple green to deep jade green but can also be blue-green (like the famous and recently rediscovered "Olmec Blue" jade), pink, lavender, and a multitude of other rare colors. Color is largely affected by the presence of trace elements such as chromium and iron. Its translucence can be anywhere from entirely solid through opaque to almost clear. Variations in color and translucence are often found even within a single specimen. Currently, the best known sources of gem quality jadeite are California, Myanmar, New Zealand and more recently Guatemala; other localities of jadeite include Kazakhstan, Russia, British Columbia, Alaska, and Turkestan.

Formation

Jadeite is formed in metamorphic rocks under high pressure and relatively low temperature conditions. Albite (NaAlSi3O8) is a common mineral of the Earth's crust, and it has a specific gravity of about 2.6, much less than that of jadeite. With increasing pressure, albite breaks down to form the high-pressure assemblage of jadeite plus quartz. Minerals associated with jadeite include: glaucophane, lawsonite, muscovite, aragonite, serpentine, and quartz.

Rocks that consist almost entirely of jadeite are called jadeitite. In all well-documented occurrences, jadeitite appears to have formed from subduction zone fluids in association with serpentinite, as discussed by Sorensen et al. (2006). Jadeitite is resistant to weathering, and boulders of jadeitite released from the serpentine-rich environments in which they formed are found in a variety of environments.

Varieties and value

Jadeite from the Motagua Valley, Guatemala is the stone used by the Olmec, Maya peoples, and the indigenous peoples of Costa Rica. Typically, the most highly valued colors of jadeite are the most intensely green, translucent varieties, though traditionally white has been considered the most valuable of the jades by the Chinese, known for their carefully crafted jade pieces.

Currently, the most highly valued variety of jadeite is known as "Imperial Green" jade, characterized by an emerald green color and a high level of translucence. It the most expensive gem in the world, carat-by-carat, costing more than diamond. "Olmec blue" jade, characterized by its deep blue-green, translucent hue with white flecking, is also becoming more highly valued because of its unique beauty and historical use by the Mesoamerican Olmec and the peoples of Costa Rica.[3] The Olmec blue variety, however, was only recently rediscovered and is being minimally exploited by native Guatemalans. It is thus difficult to obtain and too rare and little-known to have attained great value as a gemstone.

When purchasing jade, quality is determined by the degree of translucence, cleanness of color, and purity of color. Occasionally, other minerals like serpentine or quartz are sold as jade but the difference can be determined by cleavage and hardness.

See also

Notes

  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 Gemological Institute of America. 1988. Gem Reference Guide. Carlsbad, CA: Gemological Institute of America. ISBN 0-87311-019-6.
  2. The other mineral recognized as "jade" is nephrite, a green amphibole.
  3. Elizabeth Kennedy Easby, Pre-Columbian Jade from Costa Rica (New York: André Emmerich, 1968).

References
ISBN links support NWE through referral fees

  • Farndon, John. 2006. The Practical Encyclopedia of Rocks & Minerals: How to Find, Identify, Collect and Maintain the World's best Specimens, with over 1000 Photographs and Artworks. London: Lorenz Books. ISBN 0754815412 and ISBN 978-0754815419.
  • Sorensen, Sorena, George E. Harlow, and Douglas Rumble. 2006. The origin of jadeitite-forming subduction-zone fluids: CL-guided SIMS oxygen-isotope and trace-element evidence. American Mineralogist 91:979-96.

External links

  • Mindat.org. 2007. Jadeite. Mindat.org. Retrieved March 24, 2007.

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