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Apatite
Cedric Hill

Physical Geology

Spring 2008
                                                                                       Apatite
                                                                 
 

                                                   Photo 1 (Apatite – Asparagus Stone) Credited to R.Weller/Cochise College

 

 

What is Apatite?
 

            Apatite is a calcium-phosphate mineral. The name Apatite has the same pronunciation as the word “appetite” referring to the craving or being hungry for food. The name Apatite comes from the Greek spelling “apate” which means deceit. The Greek term “apate” describes Apatite perfectly because it comes Apatite comes in several different forms. Apatite also comes in many different colors mostly green or yellow but also white, red, pink, purple, brown or blue. Sometimes specimens of Apatite are colorless or even multi-colored.

 

Properties of Apatite
 

Apatite can described as “unusual partially dissolved” in some cases it can look similar to a previously sucked on piece of candy. On the Moh’s scale of hardness it is a 5, which is equivalent to the hardness of glass. This level of hardness is the reason why apatite’s cleavage is very brittle and uneven. When the material is rubbed against another material it leaves a white to yellow-gray streak. The streak of apatite can vary. Apatite’s physical appearance also varies with each specimen from transparent translucent or even opaque. Apatite has a hexagonal crystal system appearance. The density can range from 3.16 – 3.22. Apatite is a soluble mineral in sulfuric acid, nitrous acid, and hydrochloric acid.
 

Apatite (Ca5 (PO4) is a rock phosphate mineral. Apatite is an isomorphic hexagonal crystal mineral, which means apatite can exist in many different forms with other minerals as long as the base of apatite calcium (Ca5) and phosphorus (PO4) exist together. There are three common forms of apatite that appear in nature. There are many more forms but these common three are similar and sometimes hard to distinguish from each other. These minerals are Fluorapatite (Ca5 (PO4)3F), Chlorapatite (Ca5 (PO4)3Cl), and Hydroxyl apatite (Ca5 (PO4)3OH).

  

Hydroxylapatite

Photo 2 (Hydroxylapatite) Credited to www.icminerals.com

 

           Hydroxylapatite is one of the three occurring mineral forms of apatite. Hydroxylapatite consist of the base apatite calcium and phosphate bonded with hydroxide. Hydroxyl apatite is a major component in tooth enamel. Hydroxyl apatite composes 70% of bone material in the human body. Hydroxylapatite is the main mineral that tooth enamel and dentin are made of. Hydroxylapatite in tooth enamel is a very rare form because there are a few missing hydroxides. However these hydroxide ions are replaced by carbonate and acid phosphate. Tooth enamel and dentin are the strongest outer layers of the tooth. Hydroxylapatite also help in bone healing. Bones are organic and inorganic. The organic portion of bone has collagen which is a connective tissue. The inorganic portion of bone is composed of hydroxylapatite or in some cases it is called hydroxyapatite.  

 

Fluorapatite 

Photo 3 (Fluorapatite on Quartz) Credited to www.icminerals.com

 

Fluorapatite is a naturally occurring calcium phosphate in the form of hydroxyl apatite. It is also the most common form of apatite. Just like Hydroxylapatite this material also makes up the enamel in teeth. Fluorapatite is a harder material than hydroxyl apatite and also helps in protection against tooth decay. Even though Fluorapatite is a harder material than hydroxylapatite it is more resistant to acids. Fluorapatite is more resistant to acids because of sodium fluoride and sodium monofluorophosphate in toothpaste. Too much fluoride can lead to dental fluorosis.  
 

            Dental Fluorosis is a condition that is irreversible and is cause by ingestion of excessive fluoride during the tooth forming years. Dental Fluorosis can cause yellowing of the teeth, white spots, and pitting or mottling of the enamel. This can be a very undesirable look. It is the first visible sign that a child has been overexposed to fluoride. Fluorosis cannot occur once the tooth is in the oral cavity, which is why it can only happen to developing children. Mild case can involve a few spots, but severe cases can have brown stains. 

 

Pictured below are two individuals with exposure to fluoride.

The picture on the left is mild fluorosis; the picture to the right is Severe Fluorosis

  

Photo 5 & Photo 6 Fluorosis Credit to Hardy Limeback & John Colquhoun

 

 

Chlorapatite

Photo 4 (Chlorapatite mixed with biotite) Credited to © 2001 by Göran Axelsson
 

            Chlorapatite is another form of apatite, which consists of the base calcium, phosphate and Chlorine. Chlorapatite will normally come in white, yellow, and a light pinkish color. The Chlorapatite pictured above is a rare mix of Biotite which was found in Sweden. One of the best ways to distinguish Chlorapatite from other forms of apatite is because Chlorapatite will usually consist of many different crystals which will look somewhat like the one pictured below.

 

Photo 7 (Blocky Crystal of Chlorapatite) Credited to © Jeff Weissman / Photographic Guide to Mineral Species

 

Uses for Apatite
 

            Today Apatite is a widely distributed igneous, sedimentary and metamorphic rock which and are usually found in small grains. Larger crystals that are well formed can be found within other metamorphic rocks. Apatite is a main source of phosphorus that we use today; the source of phosphoric acid allows the production of pure chemicals such as sodium phosphate, mono-calcium phosphate, di-calcium phosphate as a supplement for animal food.
 

Other uses for the phosphate removed from Apatite are pharmaceuticals, ceramics, silk, textiles, insecticides, sugar refining, and manufacturing explosives. The same phosphates that are in the mineral Apatite also exist in teeth and bones of any humans and animals. Plants also use the phosphorus in the material to grow. Apatite was once extracted through crystalline structures but today they are deposited through enormous Apatite rich rock. Apatite is also a popular collectable mineral. The other important use of apatite and its rock phosphate are manufacturing elemental phosphorous. This elemental phosphorus can be used to restore damaged soil by directly applying it to the soil on the ground.
 

Apatite can be cut into gems but the softness of the specimen prevents wide-distribution and it is not as valuable to be considered a gemstone or a mineral specimen. Another reason why apatite is not a popular gemstone is because of it is so low hardness on the Moh’s scale. As state above, apatite’s level 5 of hardness makes the material only useful for earrings, brooches, and pendants. Using apatite gems as a ring stone would require extra care to prevent abrasion and loss of polish of the material.
 

Hydroxylapatite is used medically to replace amputated bone or to even promote bone growth on prosthetic implants. Coral skeletons can actually be heated at high temperatures to create hydroxylapatite. The high temperatures will burn proteins, and prevents (GVHD). (GVHD) or graft versus host disease is a common disease that may take place during bone marrow transplants. The individual’s immune system receiving the transplant will defend itself. Their antibodies will view the bone marrow as an invader even though it may be the same exact bone type.

 

Where does Apatite come from?
 

           Apatite can be deposited over many places across the world. Apatite deposits are found in there is estimation that the total world reserves around 47 billion tons of Apatite and rock phosphate. In the United States it is found in Florida, Tennessee, San Diego is most important places where Apatite is produced. Florida is the largest producer in the world and produces nearly half of the total world production. There are also many phosphate deposits running all across south of Salt Lake City in Utah traveling towards Nevada, Idaho, and Wyoming and up to Montana.
 

            The best places to find Apatite crystals are in Germany where they can range from blue to purple in colors. Colorless hexagonal Apatite can be found largely in Tyrol, Austria and Panasqueira, Portugal. Some of the largest deposits of Apatite across the world can be found in the Kola Peninsula, Russia, Nauru, Morocco, Algeria, Tunisia, Egypt, and Israel.

 

 

Photo 8 (Asparagus Stone Apatite – found in Mexico) Credited to R.Weller/Cochise College

 

Unique Information about Apatite
 

            The astrological sign of the apatite mineral is Gemini. Metaphysics is the study of the branch of philosophy that examines the nature of reality, including the relationship between mind and matter, substance and attribute, fact and value (http://dictionary.reference.com/browse/metaphysics). The metaphysical properties are as stated according to the website (www.mineralminers.com). The apatite mineral can give individuals unique special capabilities. Apatite enhances an individual’s vision, learning abilities, increase self-confidence and creativity. Others claim that the mineral Apatite helps them achieve deeper states of meditation. Apatite has said to be useful when strengthening the muscles and improving an individual’s coordination, and helps suppress hunger and ease hypertension. 

 

Rare forms of Apatite (Chart from www.minerals.net )

 

Types of Apatite                                              Chemical Formulas

Alforsite

Ba5(PO4)3Cl

Belovite

Sr3Na(Ce,La)(PO4)3Cl

Belovite-La

Sr3Na(La,Ce)(PO4)3Cl

Carbonate-fluorapatite

Ca5([PO4],[CO3])3Cl

Carbonate-hydroxylapatite

Ca5([PO4],[CO3])3OH

Fermorite

(Ca,Sr)5([P,As]O4)3OH

Fluorcaphite

(Ca,Sr,Ce,Na)5(PO4)3F

Hedyphane

Pb3Ca2(AsO4)3Cl

Johnbaumite

Ca5(AsO4)3Cl

Morelandite

(Ba,Ca,Pb)5([As,P]O4)3Cl

Strontiumapatite

(Sr,Ca)5(PO4)3(OH,F)

Svabite

Ca5(AsO4)3F

Turneurite

Ca5([As,P]O4)3Cl

 

  

 

Works Cited

 

http://www.galleries.com/minerals/phosphat/apatite/apatite.htm

 

http://www.minerals.net/mineral/phosphat/apatite/apatite.htm

 

http://www.mineralszone.com/minerals/apatite-rock-phosphate.html

 

http://www.mineraltown.com/infocoleccionar/mohs_scale_of_hardness.htm

 

http://www.mineralminers.com/html/apaminfo.htm#meta

 

http://fluoridealert.org/dental-fluorosis.htm

 

Mineral Chart http://www.minerals.net/mineral/phosphat/apatite/aptt_grp.htm

 

Photos

 

Photo 1 from http://skywalker.cochise.edu/wellerr/mineral/apatite/green1.htm

 

Photo 2 from http://www.icminerals.com/enlarged.asp?id=4027

 

Photo 3 from http://www.icminerals.com/enlarged.asp?id=3048

 

Photo 4 from http://www.geology.neab.net/index.htm

 

Photo 5 & 6 from http://fluoridealert.org/dental-fluorosis.htm

 

Photo 7 from http://webmineral.com/specimens/picshow.php?id=1714