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Chrysocolla
by Antonia Kelly
Physical Geology
Fall 2014
  
 
 

Chrysocolla

 

1

CHRYSOCOLLA SAMPLE WHICH

SHOWS COLOR AND FORMATIONS

 

HISTORY AND SCIENCE
 

     Chrysocolla is a hydrated copper silicate, which means this mineral contains water. It is an ore of copper silicate because of its continence of hydroxyl anion. The name of this copper silicate is derived from the Greek word "chrysos" meaning gold, and "kolla" meaning glue. It was given this name because of its resemblance to the material once used to solder gold.
 

     The chemical composition is (Cu,Al)2H2Si2O5(OH)4,nH2o. Chrysocolla is a special mineral. The composition of this material is a basic copper silicate with some aluminum that was absorbed. This mineral often raises questions about the structure of its composition. The rock type of chrysocolla is more of an alteration in the oxidation zone of copper minerals and deposits by the hydrothermal replacement of igneous rocks.  A more commonly used word would be pseudomorphs, after the mineral azurite in a process of metamorphism.  The many examples of pseudomorphs in the state of Arizona can include occurrences of malachite pseudomorphs after azurite.

 

     Chrysocolla is more of a mineraloid than a defined mineral.  Chrysocolla forms in a unique way, and does not have a crystalline lattice structure, like most minerals.  If exposed to the right chemical environment, over time, copper may oxidize and become malachite or azurite.  Azurite, if exposed to water, may further break down into chrysocolla. The absorption of water changes the structure. The resulting structures of chrysocolla range from a dark glassy, obsidian like rock, to an amorphous silica gel.  Chrysocolla is a copper-bearing solid substance that can be found in oxidized zones of copper veins, and found associated with azurite, malachite, cuprite, turquoise and other copper bearing minerals.

 

2

CHRYSOCOLLA TAKEN FROM

THE ASARCO COPPER MINE, RAY ARIZONA

 

     The hardness of chrysocolla on the Mohs hardness scale can range from about 1.5 to 3.5. When broken it has uneven conchoidal fractures, meaning it is a very brittle and easily broken into small flat sharp pieces.  It has no known cleavage; this is typical of most glasslike amorphous materials, without a clearly defined shape or form. The type of fractures this displays is like a series of rounded rings radiating away from the point of impact. 
 

     Chrysocolla can range, in color, from a cool blue to a greenish blue and sometimes a deep dark green. Sometimes the chrysocolla can take in other materials causing the coloration to be more black or brown from the impurities that were present when forming.  The luster or quality of the reflection under the light is a vitreous luster to almost greasy opaque look. Thinly slicing chrysocolla will give it a reflective, see-through, glasslike quality.


 

 

3

CHRYSOCOLLA CHIP TAKEN FROM

THE ASARCO COPPER MINE, RAY ARIZONA

 

     Under a microscope, chrysocolla does not present as visible crystals. Instead it will usually occur as opaque, crust-like masses, bulbous and with a melted appearance. Sometimes chrysocolla will form in fibrous or solid veins. The structures have an almost melted look. They are reminiscent of stalactite formations found in caves.

 

Industrial Uses of Chrysocolla
 

Chrysocolla has an important use for ore prospectors; Chrysocolla may suggest that there are porphyry ore deposits in the area. Porphyry ore deposits are ore bodies that formed from a hydrothermal. This will help to determine whether or not the area will be profitable to the mining company and save money in the long run.

Jewelry is another valuable importance of chrysocolla with its close resemblance to turquoise. It is too soft of a mineral to be made into jewelry on its own, though some chrysocolla found in quartz can be polished and used as cabochons or beads.   Agatized chrysocolla will have ring like bands form, and is sometimes used as beads and pendants. This is a mixture of chalcedony and quartz, which gives it an appearance of an agate.
 

4

SAMPLE OF MALACHITE, SERPENTINE, AND CHRYSOCOLLA MADE INTO A PENDANT

 

Amusing Field Tests
 

An amusing, but not necessarily safe, field test to help aid the identification of Chrysocolla would be to place a piece of the specimen in question on your tongue. Since chrysocolla adheres to moisture, the specimen would stick to your tongue.  The chrysocolla may have either a bitter or plain taste to it.

Another field test is to try to break apart the specimen. The break of chrysocolla will display more rounded, concentric rings radiating away from the point of impact, almost like a broken glass bottle.

5

PSEUDOMORPH MALACHITE CHRYSOCOLLA

AFTER AZURITE SPECIMEN WESTERN AUSTRALIA

 

 

 

 

References

Sinkankas, J., 1964, Mineralogy: Van Nostrand Reinhold, New York.

 

Thompson, J. R., 1983, Camp Verde evaporites: The Mineralogical Record, v. 14, pp. 85-90.

 

http://www.minerals.net/mineral/chrysocolla.aspx#sthash.i5qnOOLL.dpuf

 

Picture credits

 

1)  http://www.gemstoneslist.com/chrysocolla.html

2), 3) Antonia Kelly, Chrysocolla Ray Mine, Arizona 1980s

4) https://store.internationalspiritualexperience.com/en/unique-beautiful-healing-jewelry-     sale/gemstone-pendants/malachite-in-chrysocolla-and-fire-opal-sterling-silver-pendant-9

 

5) http://www.ebay.com/itm/PSEUDOMORPH-MALACHITE-CHRYSOCOLLA-AFTER-AZURITE-SPECIMEN-WESTERN-AUSTRALIA