Physical Geology 2003






Physical Characteristics

Geological process

Products of the
geological process






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Aztec mosaic of the goddess Quetzalcoatl











This thin section shows the transparency of turquoise.
Figure 1: Photo courtesy  of
Figure 1

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Such crystals are seen through a microscope.











































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Related Links

Rockhounding Arkansas

Mineralogy Database

The Mineral Galleries

Mineralogical Society
of America

The Gem Gallery

History of Native American Jewelry

Not just an accessory

Images Found on Internet, URL unknown.

Did you know Turquoise
is a mineral?


Turquoise in chemical terms is copper hydroxi phosphate.
Sometimes referred to as Callaite, this mineral from the phosphate class
ranges in color from blue to medium green. (

As seen in the variety of theses samples, greener turquoise contains more Fe (iron) and has been subjected to more moisture. ( and

Photos coutesy of,, and www.newage.comPhotos coutesy of,, and www.newage.comPhotos coutesy of,, and www.newage.comPhotos coutesy of,, and
Also known as "turkish stone", the word turquoise is a French word that
means "stone of Turkey". Reflecting this mineral's long history as
a valuable ornament, Turkey was not only a location where turquoise was mined
but also part of a trade route used to bring this mineral to Europe.

Turquoise has been mined as early as 6000 BC, and is one of the most valuable non-transparent minerals. Over time it has had ornamental use across the globe, and was very important for the first peoples of North and South American. Prehistoric Native Americans mined turquoise for ornamental use. The Zuni Indians,have been inhabitants of what is currently New Mexico for thousands of years, and are well known for their turquoise jewelry. ( ,, and

Courtesy of Aztec Turquoise Mosaic of the two headed serpent.


Physical Characteristics

Photo courtesy of

As a Hydrated Copper Aluminum Phosphate mineral, turquoise is composed of aluminum, copper, phosphorus, hydrogen and oxygen. Turquoise is an example of a typical phosphate as it is often strongly colored and average in hardness ( and


Strike: White
Hardness: 5-6
Luster: Dull to Waxy
Transparency: semi-transparent to opaque (FIGURE 1)
Crystal Habits: Crystals rarely visible without microscope
Fracture: Conchoidal and smooth
Cleavage: Perfect in 2 directions, rarely seen.
Specific Gravity: 2.6-2.9
Chemistry: CuA16(P0 4)4(OH)8 4H20

Courtesy of
(Perkins p472, and

Geologic Processes of
Copper Hydroxi Phosphate

Images Found on Internet, URL unknown.Photo courtesy of www.cscmu.eduPhoto courtesy of courtesy of The mineral forms in association with copper deposits, or in other words it forms as a secondary mineral. Copper transported in water interacts with
phosphorous and aluminum-bearing rocks.

Turquoise is associated with Al-rich (aluminum rich) volcanic rocks association with copper deposits. The majority of turquoise is found in regions with volcanic or thermal history. Most turquoise forms in locations where magmatic solutions have intruded into fractures or pores.

Immense heat and chemical changes between the protolith and new rock are other necessary conditions. After this process, chemical weathering (water solutions and air) over a long period of time allows the mineral to form.
Courtesy of

Finally, the mineral forms when the chemical compound CuA16(P0 4)4(OH)8 4H20 dissolves into water that has been deposited into veins, seams, stringers and crusts. (Perkins and

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Turquoise of blue and blue-green can be found in large amounts at Mount Ali Mirsai in Iran. The mineral is also found in Arizona, Nevada and New Mexico, US; Australia; Iran; Afghanistan and other areas of the Middle East. (Novak 1999 and




Products of the Geologic Process

Iron pyrites and sometimes bits of quartz create blotches and dark lines found in many turquoise specimens.
Photo courtesy of
Quality turquoise can be sold by the piece, and then the remainder is sold or processed for sale by weight.

Turquoise that is hard, dense and with an inherent luster can be cut, shaped and polished directly after being mined, without any additives.

Other turquoise must be stabilized with a resin or treated to improve color. ( and

Photo Courtesy of


Mass-market mining of turquoise as a gemstone or by-product has had large impacts. Though it has been mined for thousands of years, unfortunately this resource is in shorter supply as the demand for it has increased.
Because turquoise is a valuable and nonrenewable ore resource, the demand for this gemstone will only increase with restricted production. For example, in Arizona, turquoise is still the most important gemstone being produced. However, as Arizona's resources have become exhausted, Arizona's Morenci Mine and the deposits at Bisbee are producing very little. (
According Professor Johnson at Northern Kentucky University, there are only 3 working mines in the USA are currently producing gem grade turquoise. (

This photo courtesy of H. Milford and  www.cerrillowshills.orgFound on web, source unknown




Synthetic turquoise jewelry may not be ascetically pleasing.
However, if mining continues at today's rate, “fake” turquoise may someday become
our only reminder of this valuable mineral.


"History of Turquoise" Americana,

"History of Turquoise" Americana,

"History of Turquoise" Matriq

Novak, Milan and Korbel, Petr, Minerals Encyclopedia, Rebo Productions, The Netherlands 1999 p182

"ARIZONA MINING UPDATE – for 1999" Phillips, K.A. , Niemuth, N.J.,
Arizona Department of Mines and Mineral Resources

"The mineral turquoise", The Mineral Gallery,, Amethyst Galleries, Inc. 1996

"Turquoise", The Gem Gallery

"Turquoise Mineral Data", Mineralogy Database 2002

"Turquoise", Desert USA 2003

"Lecture 16",

Perkins, Dexter "Mineralogy: Second Edition" Prentice Hall New Saddle River, Jersey 2002 pp472, 397

“Outline for Earth’s Resources” Professor Johnson, Northern Kentucky University

"Zuni Pueblo" Key to Any City


Photo courtesy of

Additional Sources on Mineralogy and Turquoise Available at Earlham College Libraries

Beryllium : mineralogy, petrology, and geochemistry / editor, Edward S. Grew. 2002.
Earlham -- Wildman Sci QD181.B4 B47 2002 c.1

Bliss, James D. Preliminary mineral resource assessment of selected industrial and collector minerals of the Prescott National Forest, Arizona [microform] / by James D. Bliss. 1999.
Earlham -- Lilly Microforms I 19.76:99-305 c.1 NonCirculating

Transformation processes in minerals / editors, Simon A.T. Redfern & Michael A. Carpenter. c2000.
Earlham -- Wildman Sci QE364 .T73 2000 c.1

Bishop, A. C. (Arthur Clive) Cambridge guide to minerals, rocks, and fossils / A.C. Bishop, A.R. Woolley, W.R. Hamilton. c1999.
Earlham -- Wildman Sci QE363.8 .B56 1999 c.1

Hurlbut, Cornelius Searle, 1906- Dana's minerals and how to study them : (after Edward Salisbury Dana). c1998.
Earlham -- Wildman Sci QE365 .H845 1998 c.1

Hochleitner, Rupert. Minerals : identifying, learning about, and collecting the most beautiful minerals and crystals / Rupert Hochleitner. [1994]
Earlham -- Wildman Sci QE373.2 .H6413 1994 c.1

MacKenzie, W. S. A color atlas of rocks and minerals in thin section / W.S. MacKenzie, A.E. Adams. c1994.
Earlham -- Wildman Sci QE434 .M33 1994 c.1

Dana, Edward Salisbury, 1849-1935. Minerals, and how to study them. A book for beginners in mineralogy. With more than 300 illustrations. 1896.
Earlham -- Wildman Sci QE365 .D16 c.1

Kaplan, Stuart R., A guide to information sources in mining, minerals, and geosciences, edited by Stuart R. Kaplan. [1965]
Earlham -- Wildman Reference SciRef QE26 .K3 c.1 NonCirculating

Loomis, Frederic Brewster, b. 1873. Field book of common rocks and minerals : for identifying the rocks and minerals of the United States and interpreting their origins and meanings. [1948]



Author: Laura Norlin
Creation/revision date: April 5th, 2003

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