Tiger's eye: Difference between revisions

Tiger's eye
Tiger's eye
General
Category	Mineral
Formula; (repeating unit)	Silica (silicon dioxide, SiO2)
Identification
Colour	golden to red-brown
Mohs scale hardness	5.5 - 6
Luster	Silky
Specific gravity	2.64 – 2.71

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Tiger's eye (also called tiger eye) is a chatoyant gemstone that is usually a metamorphic rock with a golden to red-brown colour and a silky lustre. As members of the quartz group, tiger's eye and the related blue-coloured mineral hawk's eye gain their silky, lustrous appearance from the parallel intergrowth of quartz crystals and altered amphibole fibres that have mostly turned into limonite.^[1]^[2]

Other forms of tiger's eye

Tiger iron is an altered rock composed chiefly of tiger's eye, red jasper and black hematite. The undulating, contrasting bands of colour and lustre make for an attractive motif and it is mainly used for jewellery-making and ornamentation. Tiger iron is a popular ornamental material used in a variety of applications, from beads to knife hilts.

Tiger iron is mined primarily in South Africa and Western Australia. Tiger's eye is composed chiefly of silicon dioxide (SiO₂) and is coloured mainly by iron oxide. The specific gravity ranges from 2.64 to 2.71.^[3] It is formed by the alteration of crocidolite.

Serpentine deposits in which are occasionally found chatoyant bands of chrysotile fibres have been found in the US states of Arizona and California. These have been cut and sold as "Arizona tiger-eye" and "California tiger's eye" gemstones.^[4]^[5] The trade name of pietersite is used for a fractured or brecciated chalcedony containing amphibole fibers and promoted as tiger's eye from Namibia and China.^[6]

Sources

Common sources of tiger's eye include Australia, Burma, India, Namibia, South Africa, the United States,^[7] Brazil, Canada, China, Korea and Spain.^{[citation needed]}

Cultural associations

In some parts of the world, the stone is believed to ward off the evil eye. ^[8]

Cut, treatment and imitation

Gems are usually given a cabochon cut to best display their chatoyance. Red stones are developed by gentle heat treatments. Dark stones are artificially lightened to improve colour using a nitric acid treatment.^[9]

Honey-coloured stones have been used to imitate the more valued cat's eye chrysoberyl (cymophane), but the overall effect is often unconvincing. Artificial fibre optic glass is a common imitation of tiger's eye, and is produced in a wide range of colours.

References

^ "Tiger's Eye". mindat.org. Retrieved 16 May 2016.
^ Heaney, Peter; Fisher, Donald (April 2003). "New interpretation of the origin of tiger's-eye". Geology. 31 (4): 323–326. doi:10.1130/0091-7613(2003)031<0323:NIOTOO>2.0.CO;2. Retrieved 16 May 2016.
^ Listing of SG of gems and gem simulants, Berkeley.edu
^ Flagg, Arthur Leonard (1958). Mineralogical Journeys in Arizona. Scottsdale: F.H. Bitner. pp. 92–93.
^ USGS (1908–1909). "Cat's Eye or Tiger-Eye". Mineral Resources of the United States / Department of the Interior, United States Geological Survey. 2. Washington, D.C.: US Government Printing Office: 802.
^ Pietersite on Mindat.org
^ Schumann, Walter (2009). Gemstones of the World (Fourth ed.). New York, New York: Sterling Publishing. p. 140. ISBN 978-1-4027-6829-3.
^ The Encyclopedia of Superstitions By Richard Webster, p.257
^ O'Donoghue, Michael (1997). Synthetic, Imitation, and Treated Gemstones. Boston, Massachusetts: Butterworth-Heinemann. pp. 125–127. ISBN 0-7506-3173-2.

External links

[1] New interpretation of the origin of tiger's-eye: Comment and Reply

[1] "Tiger's Eye". mindat.org. Retrieved 16 May 2016.

[2] Heaney, Peter; Fisher, Donald (April 2003). "New interpretation of the origin of tiger's-eye". Geology. 31 (4): 323–326. doi:10.1130/0091-7613(2003)031<0323:NIOTOO>2.0.CO;2. Retrieved 16 May 2016.

[3] Listing of SG of gems and gem simulants, Berkeley.edu

[4] Flagg, Arthur Leonard (1958). Mineralogical Journeys in Arizona. Scottsdale: F.H. Bitner. pp. 92–93.

[5] USGS (1908–1909). "Cat's Eye or Tiger-Eye". Mineral Resources of the United States / Department of the Interior, United States Geological Survey. 2. Washington, D.C.: US Government Printing Office: 802.

[6] Pietersite on Mindat.org

[7] Schumann, Walter (2009). Gemstones of the World (Fourth ed.). New York, New York: Sterling Publishing. p. 140. ISBN 978-1-4027-6829-3.

[8] The Encyclopedia of Superstitions By Richard Webster, p.257

[9] O'Donoghue, Michael (1997). Synthetic, Imitation, and Treated Gemstones. Boston, Massachusetts: Butterworth-Heinemann. pp. 125–127. ISBN 0-7506-3173-2.

[1]

@@ Line 4: / Line 4: @@
 | image       = Tiger's eye.jpg
 | imagesize   = 260px
-| alt         = A photograph showing a polished reddish brown stone which is bisected by a band containing golden fibers
+| alt         = A polished reddish brown stone which is bisected by a band containing golden fibers
 | caption     =
 | formula     = Silica ([[silicon dioxide]], SiO<sub>2</sub>)
@@ Line 25: / Line 25: @@
 '''Tiger's eye''' (also called '''tiger eye''') is a
-[[Chatoyancy|chatoyant]] [[gemstone]] that is usually a [[metamorphic rock]] with a golden to red-brown colour and a [[Lustre (mineralogy)#Silky lustre|silky lustre]]. As members of the [[quartz]] group, Tiger's eye and the related blue-coloured mineral Hawk's eye gain their silky, lustrous appearance from the parallel intergrowth of quartz crystals and altered [[amphibole]] fibres that have mostly turned into [[limonite]].<ref>{{cite web|title=Tiger's Eye|url=http://www.mindat.org/min-3960.html|website=mindat.org|accessdate=16 May 2016}}</ref><ref>{{cite journal|last1=Heaney|first1=Peter|last2=Fisher|first2=Donald|title=New interpretation of the origin of tiger's-eye|journal=Geology|date=April 2003|volume=31|issue=4|pages=323–326|doi=10.1130/0091-7613(2003)031<0323:NIOTOO>2.0.CO;2|url=http://geology.gsapubs.org/content/31/4/323.short|accessdate=16 May 2016}}</ref>
+[[Chatoyancy|chatoyant]] [[gemstone]] that is usually a [[metamorphic rock]] with a golden to red-brown colour and a [[Lustre (mineralogy)#Silky lustre|silky lustre]]. As members of the [[quartz]] group, 's eye and the related blue-coloured mineral 's eye gain their silky, lustrous appearance from the parallel intergrowth of quartz crystals and altered [[amphibole]] fibres that have mostly turned into [[limonite]].<ref>{{cite web|title=Tiger's Eye|url=http://www.mindat.org/min-3960.html|website=mindat.org|accessdate=16 May 2016}}</ref><ref>{{cite journal|last1=Heaney|first1=Peter|last2=Fisher|first2=Donald|title=New interpretation of the origin of tiger's-eye|journal=Geology|date=April 2003|volume=31|issue=4|pages=323–326|doi=10.1130/0091-7613(2003)031<0323:NIOTOO>2.0.CO;2|url=http://geology.gsapubs.org/content/31/4/323.short|accessdate=16 May 2016}}</ref>
 {{TOC left}}
 {|style="margin: 0 auto;"
  | [[File:Quartz - Tigers-Eye - raw stone from Southafrica.jpg|thumb|left|alt="Photograph of a chunk of rock containing horizontal bands which contain golden fibers which are positioned vertically within the bands"|Unpolished tiger eye from South Africa]]
 | [[File:Tigers eye egg shape.jpg|thumb|left|alt="Photograph of a polished ovoid stone with bands containing shimmering golden fibers"|Oval shape tiger's eye with iron stripes]]
 |}
@@ Line 34: / Line 34: @@
 ==Other forms of tiger's eye==
 [[File:tiger iron.jpg|thumb|right|alt="Photograph of the surface of a stone which shows horizontal alternating bands of red and black with a band of golden-colored fibers in a band across the center"|Tiger iron]]
-''Tiger iron'' is an altered [[rock (geology)|rock]] composed chiefly of tiger's eye, red [[jasper]] and black [[hematite]]. The undulating, contrasting bands of colour and lustre make for an attractive motif, and it is mainly used for jewellery-making and ornamentation. Tiger iron is a popular ornamental material used in a variety of applications, from beads to [[knife]] [[hilt]]s.
+''Tiger iron'' is an altered [[rock (geology)|rock]] composed chiefly of tiger's eye, red [[jasper]] and black [[hematite]]. The undulating, contrasting bands of colour and lustre make for an attractive motif and it is mainly used for jewellery-making and ornamentation. Tiger iron is a popular ornamental material used in a variety of applications, from beads to knife [[hilt]]s.
-Tiger iron is mined primarily in [[South Africa]] and [[Western Australia]]. Tiger's eye is composed chiefly of [[silicon dioxide]] (SiO<sub>2</sub>) and is coloured mainly by iron oxide. The [[specific gravity]] ranges from 2.64 to 2.71.<ref>[http://ist-socrates.berkeley.edu/~eps2/wisc/sg.html Listing of SG of gems and gem simulants], Berkeley.edu</ref> It is formed by the alteration of crocidolite.
+Tiger iron is mined primarily in South Africa and Western Australia. Tiger's eye is composed chiefly of [[silicon dioxide]] (SiO<sub>2</sub>) and is coloured mainly by iron oxide. The [[specific gravity]] ranges from 2.64 to 2.71.<ref>[http://ist-socrates.berkeley.edu/~eps2/wisc/sg.html Listing of SG of gems and gem simulants], Berkeley.edu</ref> It is formed by the alteration of crocidolite.
 {{clear}}
 [[File:Chatoyant serpentine 01.jpg|thumb|right|alt="A photograph of a green stone with a pink fibrous band going across the surface diagonally"|Serpentine tiger's eye from Arizona]]
@@ Line 43: / Line 43: @@
 ==Sources==
-Common sources of tiger's eye include [[Australia]], [[Burma]], [[India]], [[Namibia]], [[South Africa]], [[United States]],<ref>{{cite book|last=Schumann|first=Walter|title=Gemstones of the World|year=2009|publisher=Sterling Publishing|location=New York, New York|isbn=978-1-4027-6829-3|edition=Fourth|page=140}}</ref> [[Brazil]], [[Canada]], [[China]], [[Korea]]  and [[Spain]].{{Citation needed|date=August 2011}}
+Common sources of tiger's eye include Australia, Burma, India, Namibia, South Africa, United States,<ref>{{cite book|last=Schumann|first=Walter|title=Gemstones of the World|year=2009|publisher=Sterling Publishing|location=New York, New York|isbn=978-1-4027-6829-3|edition=Fourth|page=140}}</ref> Brazil, Canada, China, Korea  and Spain.{{Citation needed|date=August 2011}}
 ==Cultural associations==
@@ Line 50: / Line 50: @@
 ==Cut, treatment and imitation==
-Gems are usually given a [[cabochon]] cut to best display their [[chatoyance]]. Red stones are developed by gentle heat treatment. Dark stones are artificially lightened to improve color using a [[nitric acid]] treatment.<ref>{{cite book|last=O'Donoghue|first=Michael|title=Synthetic, Imitation, and Treated Gemstones|year=1997|publisher=Butterworth-Heinemann|location=Boston, Massachusetts|isbn=0-7506-3173-2|pages=125–127}}</ref>
+Gems are usually given a [[cabochon]] cut to best display their [[chatoyance]]. Red stones are developed by gentle heat . Dark stones are artificially lightened to improve  using a [[nitric acid]] treatment.<ref>{{cite book|last=O'Donoghue|first=Michael|title=Synthetic, Imitation, and Treated Gemstones|year=1997|publisher=Butterworth-Heinemann|location=Boston, Massachusetts|isbn=0-7506-3173-2|pages=125–127}}</ref>
-Honey-colored stones have been used to imitate the more valued cat's eye [[chrysoberyl]] (cymophane), but the overall effect is unconvincing. Artificial [[optical fiber|fibre optic]] glass is a common imitation of tiger's eye, and is produced in a wide range of colours. Tiger's eye comes primarily from [[South Africa]] and [[east Asia]].
+Honey- stones have been used to imitate the more valued cat's eye [[chrysoberyl]] (cymophane), but the overall effect is unconvincing. Artificial [[optical fiber|fibre optic]] glass is a common imitation of tiger's eye, and is produced in a wide range of colours.
 ==References==