Everything about Apatite totally explained
Apatite is a group of
phosphate minerals, usually referring to
hydroxylapatite,
fluorapatite, and
chlorapatite, named for high concentrations of
OH−,
F−, or
Cl− ions, respectively, in the
crystal. The formula of the admixture of the three most common
endmembers is written as
Ca5(
PO4)
3(OH, F, Cl), and the formulae of the individual
minerals are written as
Ca
5(PO
4)
3(OH), Ca
5(PO
4)
3F and Ca
5(PO
4)
3Cl, respectively.
Apatite is one of few minerals that are produced and used by biological micro-environmental systems. Hydroxylapatite is the major component of
tooth enamel. A relatively rare form of apatite in which most of the OH groups are absent and containing many carbonate and acid phosphate substitutions is a large component of
bone material.
Fluorapatite (or fluoroapatite) is more resistant to acid attack than is hydroxyapatite. For this reason, toothpaste typically contain a source of fluoride
anions (for example sodium fluoride,
sodium monofluorophosphate). Similarly,
fluoridated water allows exchange in the
teeth of fluoride ions for
hydroxyl groups in apatite. Too much fluoride results in
dental fluorosis and/or
skeletal fluorosis.
In the
United States, apatite is often used to fertilize
tobacco. It partially starves the plant of
nitrogen, which gives American
cigarettes a different taste from those of other countries.
Fission tracks in apatite are commonly used to determine the thermal history of orogenic (mountain) belts and of sediments in
sedimentary basins.
(U-Th)/He dating of apatite is also well-established for use in determining thermal histories and other, less typical applications such as paleo-wildfire dating.
Phosphorite is a phosphate-rich
sedimentary rock, that contains between 18% and 40% P
2O
5. The apatite in phosphorite is present as
cryptocrystalline masses referred to as
collophane.
Gemology
Apatite is infrequently used as a
gemstone.
Transparent stones of clean color have been faceted, and
chatoyant specimens have been
cabochon cut. Crystals of rutile may have grown in the crystal of apatite so when in the right light, the cut stone displays a cat's eye effect. Major sources for gem apatite are. This is preferable to traditional rare earth ores, as Apatite is non-radioactive and doesn't pose an environmental hazard in
mine tailings.
Apatite is an ore mineral at the
Hoidas Lake rare earth project.
Further Information
Get more info on 'Apatite'.
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