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Roger Weller, geology instructor                                         

wellerr@cochise.edu
Quartz Family Gemstones-by Audrey LaClair 
                            
                          Tigereye or Tiger's Eye


          Tiger's eye starts out as a blue mineral called crocidolite, which happens to be fibrous.  Crocidolite is actually what we know as asbestos.  It starts to transform into tigereye when quartz starts becoming embedded in the crocidolite.  When this happens, one of two gemstones is formed.  It is either Tiger's eye or Hawk's eye.  When this happens, the asbestos dissolves completely.  The quartz then changes into fibrous formations and retains the blue color from the crocidolite.  Because of this, it creates parallel lines in the gem that creates the light shift and movement; which is also known as chatoyancy.  The gleam that rolls across the surface is like the eyes of a cat.  Geological conditions then change the color of tigereye into a deep yellow, brown,  green, and rarely blue.  It can turn red by heating, either naturally or artificially.


photo by R.Weller

 

         "The gems are usually cut en cabochon in order to best display their chatoyancy. Red stones are brought about through gentle heat treatment. Honey-coloured stones have been used to imitate the much higher valued cat's eye chrysoberyl (cymophane), but the overall effect is unconvincing" ( http://en.wikipedia.org/wiki/Tiger's_eye). 
 

         Tigereye is most frequently found in South Africa.  Unfortunately, on May 10, 1968, Carol de Wet announced an embargo on the exportation of rough tigereye.  This led to all rough export being eliminated by May of 1971.  This was to create a South African monopoly on the finished tigereye.  Now, all rough tigereye is being smuggled out of the country in huge quantities instead of being legally exported.  This rough tigereye is finished in other countries and then sold out as a profit.  Tiger's eye can also be found in the USA, Canada, Western Australia, Namibia, Burma, and India.
 


photo by R.Weller

 

         "Tiger's Eye is the Planetary stone for Gemini (May 21-Jun. 20) and the accepted gem for the ninth wedding anniversary" ( http://www.bernardine.com/gemstones/tigers-eye.htm ).

         There are many legends that say if one wears tiger's eye, it will be beneficial for both spiritual well being and health.  Another legend says it is great for business, aids to achieving clarity, and a psychic protector.

 


photo by R.Weller

 

Physical Properties
 

Color - various shades of golden or honey yellow and various brown hues, typically roughly striped
H. (effective hardness) 6.5 - 7
S.G. ~ 2.65 - 2.9.

Light transmission - subtranslucent to opaque
Luster - a silky sheen that is improved markedly by cutting and polishing
Breakage - subconchoidal to irregular

From ( http://www.cst.cmich.edu/users/dietr1rv/hawkseye.htm ).

 
References:

http://www.minerals-n-more.com/Tiger_Eye_Info.html
http://en.wikipedia.org/wiki/Tiger's_eye
http://www.cst.cmich.edu/users/dietr1rv/hawkseye.htm
http://www.bernardine.com/gemstones/tigers-eye.htm
http://www.lapidaryjournal.com/feature/jul00str.cfm
http://www.minerals-n-more.com/Tiger_Eye_Info.html