The World of Quartz
"Coarsely Crystalline Quartz"

Stone Junod's Web Page
for
GO 336 Mineralogy
at Emporia State University


Amethyst
Image taken by:  Hershel Friedman
From:  http://minerals.net/mineral/silicate/tecto/quartz/images/quartz/gifs/amthyst1.htm





I am a student attending Emporia State University.  My major is Earth
Science.  I intend to graduate in May of 2001.  GO  336 "Mineralogy"
is one of the core courses required to complete my Bachelors of Science degree and this web page fulfills one of the requirements for this course.  I chose quartz because I consider it to be one of the
most beautiful, commonly occurring minerals in all of Creation! Quartz possesses
several fascinating characteristics and uses.  It is my privilege to
introduce to you, World of Quartz. 










Table of Contents





                  
            


  
    

      Crystallography
      Physical Properties

      		
    

    

      Composition &
Structure

      		
      Varieties

      		
    

    

      Occurrence

      		
      Use

      		
    

    

       Links 

      		
      References

      		
    

            
  











Crystallography



     Quartz belongs to the hexagonal crystal system.  Quartz
crystals are usually prismatic with horizontally striated faces and terminated
by double rhombohedrons or right and left handed trigonal trapezohedrons (3). 
Quartz can also be granular, disseminated, and massive.






Physical Properties



       Quartz has a hardness of 7 on the Mohs Hardness Scale.  The specific gravity is average for a nonmetallic at 2.65.  A conchoidal
fracture will result when quartz is struck and it has no cleavage. Pure quartz is usually white
or colorless and the streak is white.  Impurities may contribute to an array of various
colors.  Quartz is transparent to translucent. The physical properties
of this mineral always remain constant.  The luster of quartz is vitreous
and in some specimens greasy.








Composition and Structure



      The chemical composition for Quartz is SiO2, with a chemical breakdown of approximately 46.7% silicon and 53.3% oxygen.  Quartz is easily transformed from low to high quartz at 573 degrees Celsius with only minor atomic adjustments and without breaking any of the Si-O bonds.








Varieties of Coarsely Crystalline Quartz




      Quartz exists in many different and exciting varieties. 
Impurities may add color and character to the quartz, however the composition
will always remain virtually the same, 100% SiO2.

 

        Rock Crystal - A
colorless, transparent variety of quartz, free from most impurities and often
found in distinct crystals.



        Amethyst - Often
found in crystals, this variety of quartz possesses various shades of purple. 
It receives its color from trace amounts of iron and magnesium.



         Rose Quartz - Usually
without crystal form, it is rose-red to pink in color.  This is due
to small amounts of thallium.



        Smoky Quartz - Frequently
found in crystal form,it is smokey yellow to brown to almost black in color
due to trace amounts of aluminum.



         Citrine - Quartz
of a light yellow variety resembling topaz in color.











Citrine Quartz

Image taken by: Hershel Friedman

From: 
http://minerals.net/mineral/silicate/tecto/quartz/imagesquartz/gifs/citrine1.htm






         Milky Quartz -
This quartz is milky white in color due to fluid inclusions.  It often
possesses a greasy luster.



        Cat's eye and Tiger's eye - Quartz of these varieties
contain parallel fibrous inclusions creating a chatoyancy.



        Rutilated quartz - Quartz with fine rutile inclusions
penetrating it.



        Aventurine quartz - This variety of quartz contains
tiny scales of colored minerals such as mica and hematite.



 





Occurrence



      Quartz is the most common and abundant mineral in all
Creation.  It is commonly found in igneous and metamorphic rocks. 
Quartz often exists in abundance in hydrothermal and metal bearing veins. 
Quartz is a major constituent of granites.  Since quartz is the most
abundant mineral in the world it is commonly found virtually everywhere, including
the United States.  

    

     Common quartz localities in the United States.



    Rock crystal - Hot Springs, Arkansas,
and Little Falls, Herkimer County, New York.



    Amethyst - Delaware and Chester
counties, Pennsylvania; and Oxford County, Maine.



    Rose Quartz  - California,
Maine, Montana, and South Dakota.



    Smoky Quartz - Pikes Peak, Colorado;
Alexander County, North Carolina; and Oxford County, Maine.








Use 



      The word quartz a German word derived from ancient times. 
Its various varieties were used as gemstones and ornamental items by the ancients. 
Today, quartz is still appreciated for its gem quality, however it is also used
in a variety of other ways.  Sand size quartz granules are used in mortar,
concrete, as an abrasive or flux, and in the manufacturing of such items
as silica brick and glass.  Quartz, when broken down into a powder form,
can be used in paints, porcelain, sandpaper, wood filler, and scouring soaps. 
Quartz cut into prisms and lenses are used for scientific equipment. 
Quartz plates are used in watches while quartz oscillators are used to control
radio frequencies.  Quartz is also used in the production of a variety
of electrical components.  In the computer industry all silicon semiconductors
are made from quartz.








Links 



GO 336 Mineralogy  
http://www.emporia.edu/earthsci/amber/go336/index.htm



Mineralogy Database  http://www.webmineral.com/



The Mineral Gallery  http://mineral.galleries.com/



The Mineral and Gemstone Kingdom  http://minerals.net/






References:




    
  
  
  1.  Amethyst Galleries' Mineral Gallery.  Last modified:  Thursday,
12 April 2001. Retrieved:  12 April 2001. 
http://mineral.galleries.com/ 
    2. 
  
  
  2.  Chesterman, Charles W.  National Audubon Society Field Guide to
North American Rocks and Minerals.  New York:  Chanticleer Press,
Inc.,1998.
    3. 
  
  
  3.  Hurlbut, C. S. Jr. and Cornelis Klein.  Manual of Mineralogy. 
New York:  John Wiley & Sons, 21st Edition, 1997.
    4. 
  
  
  4.  Microsoft Encarta Encyclopedia.  Microsoft corporation, 1993-1997.
    5. 
  
  
  5.  The Mineral and Gemstone Kingdom.  Quartz.  Created: 
1999.  Retrieved:  20 February 2001.  Hershel Friedman.  
    http://minerals.net/
    6. 
  
  
  6. Mineralogy GO 336.  Last Modified:   10 January 2001. 
Retrieved:  12 April 2001.  Susan Ward Aber.   
http://www.emporia.edu/earthsci/amber/go336/index.htm
    7. 
  
  
  7.  Mineralogy Database.  Last Modified:  Wednesday, 11 April
2001.  Retrieved:  12 April 2001.   David Barthelmy.  
  http://www.webmineral.com/
    8. 





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