Naturally occurring mineral form of calcium apatite
Hydroxyapatite
Hydroxyapatite crystals on matrix
General
Category
Phosphate mineral Apatite group
Formula (repeating unit)
Ca5(PO4)3OH
IMA symbol
Hap[1]
Strunz classification
8.BN.05
Crystal system
Hexagonal
Crystal class
Dipyramidal (6/m) H-M symbol (6/m)
Space group
P63/m
Unit cell
a = 9.41 Å, c = 6.88 Å; Z = 2
Identification
Formula mass
502.31 g/mol
Color
Colorless, white, gray, yellow, yellowish green
Crystal habit
As tabular crystals and as stalagmites, nodules, in crystalline to massive crusts
Cleavage
Poor on {0001} and {1010}
Fracture
Conchoidal
Tenacity
Brittle
Mohs scale hardness
5
Luster
Vitreous to subresinous, earthy
Streak
White
Diaphaneity
Transparent to translucent
Specific gravity
3.14–3.21 (measured), 3.16 (calculated)
Optical properties
Uniaxial (−)
Refractive index
nω = 1.651 nε = 1.644
Birefringence
δ = 0.007
References
[2][3][4]
HydroxyapatiteNeedle-like hydroxyapatite crystals on stainless steel. Scanning electron microscope picture from University of Tartu.Nanoscale coating of Ca-HAp, image taken with scanning probe microscopeA 3D visualization of half of a hydroxyapatite unit cell, from x-ray crystallography
Hydroxyapatite (IMA name: hydroxylapatite[5]) (Hap, HAp, or HA) is a naturally occurring mineral form of calcium apatite with the formula Ca5(PO4)3(OH), often written Ca10(PO4)6(OH)2 to denote that the crystal unit cell comprises two entities.[6] It is the hydroxyl endmember of the complex apatite group. The OH− ion can be replaced by fluoride or chloride, producing fluorapatite or chlorapatite. It crystallizes in the hexagonal crystal system. Pure hydroxyapatite powder is white. Naturally occurring apatites can, however, also have brown, yellow, or green colorations, comparable to the discolorations of dental fluorosis.
Up to 50% by volume and 70% by weight of human bone is a modified form of hydroxyapatite, known as bone mineral.[7] Carbonated calcium-deficient hydroxyapatite is the main mineral of which dental enamel and dentin are composed. Hydroxyapatite crystals are also found in pathological calcifications such as those found in breast tumors,[8] as well as calcifications within the pineal gland (and other structures of the brain) known as corpora arenacea or "brain sand".[9]
^Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C., eds. (2000). "Hydroxylapatite". Handbook of Mineralogy(PDF). Vol. IV (Arsenates, Phosphates, Vanadates). Chantilly, VA, US: Mineralogical Society of America. ISBN 978-0962209734. Archived (PDF) from the original on 2018-09-29. Retrieved 2010-08-29.
^"The official IMA-CNMNC List of Mineral Names". International Mineralogical Association: COMMISSION ON NEW MINERALS, NOMENCLATURE AND CLASSIFICATION. Retrieved 24 August 2023.
^Singh, Anamika; Tiwari, Atul; Bajpai, Jaya; Bajpai, Anil K. (2018-01-01), Tiwari, Atul (ed.), "3 – Polymer-Based Antimicrobial Coatings as Potential Biomaterials: From Action to Application", Handbook of Antimicrobial Coatings, Elsevier, pp. 27–61, doi:10.1016/b978-0-12-811982-2.00003-2, ISBN 978-0-12-811982-2, retrieved 2020-11-18
^
Junqueira, Luiz Carlos; José Carneiro (2003). Foltin, Janet; Lebowitz, Harriet; Boyle, Peter J. (eds.). Basic Histology, Text & Atlas (10th ed.). McGraw-Hill Companies. p. 144. ISBN 978-0-07-137829-1. Inorganic matter represents about 50% of the dry weight of bone ... crystals show imperfections and are not identical to the hydroxylapatite found in the rock minerals
^Haka, Abigail S.; Shafer-Peltier, Karen E.; Fitzmaurice, Maryann; Crowe, Joseph; Dasari, Ramachandra R.; Feld, Michael S. (2002-09-15). "Identifying microcalcifications in benign and malignant breast lesions by probing differences in their chemical composition using Raman spectroscopy". Cancer Research. 62 (18): 5375–5380. ISSN 0008-5472. PMID 12235010.
^Angervall, Lennart; Berger, Sven; Röckert, Hans (2009). "A Microradiographic and X-Ray Crystallographic Study of Calcium in the Pineal Body and in Intracranial Tumours". Acta Pathologica et Microbiologica Scandinavica. 44 (2): 113–19. doi:10.1111/j.1699-0463.1958.tb01060.x. PMID 13594470.
Hydroxyapatite (IMA name: hydroxylapatite) (Hap, HAp, or HA) is a naturally occurring mineral form of calcium apatite with the formula Ca5(PO4)3(OH), often...
calcified/calcareous tendinitis/tendinopathy, tendinosis calcarea, hydroxyapatite deposition disease, calcific periarthritis A plain X ray of the shoulder...
with the introduction of spherical implants made of porous calcium hydroxyapatite. This material allows for fibrovascular ingrowth within several months...
it is hydroxyapatite if the extra ion is mainly hydroxide. Much of the "tricalcium phosphate" on the market is actually powdered hydroxyapatite. Tricalcium...
hydroxyphosphate (calcium phosphate tribasic, tribasic calcium phosphate, hydroxyapatite, HAp) is an inorganic chemical compound that is made up of calcium,...
Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of OH−, F− and Cl− ion, respectively...
Meat and bone meal (MBM) is a product of the rendering industry. It is typically about 48–52% protein, 33–35% ash, 8–12% fat, and 4–7% water. It is primarily...
biomedical applications because of its similar composition to that of hydroxyapatite, the mineral component of bone. This similarity provides Bioglass 45S5's...
material. The two major components of bone are hydroxyapatite [Ca10(PO4)6(OH)2], and collagen fibers. Hydroxyapatite, which is one of the most stable forms of...
it is made; however, it consists mainly of tricalcium phosphate (or hydroxyapatite) 57–80%, calcium carbonate 6–10% and carbon 7–10%. It is primarily used...
microcrystalline hydroxyapatite and to compare its efficacy with other forms of calcium supplementation. Ossein-hydroxyapatite and microcrystalline hydroxyapatite, both...
structures are made of crystalline calcium phosphate in the form of hydroxyapatite. The hard dense enamel of mammalian teeth may contain fluoroapatite...
which include bioceramics such as dental implants and synthetic bones. Hydroxyapatite, the major mineral component of bone, has been made synthetically from...
N-protection of amines and amides. Doping MgO (about 1–5% by weight) into hydroxyapatite, a bioceramic mineral, increases the fracture toughness by migrating...
biomineral composite constructed from collagen fibers mineralized with hydroxyapatite. This composite lends ivory the impressive mechanical properties—high...
supply calcium and phosphorus to monogastric livestock in the form of hydroxyapatite. As a slow-release organic fertilizer, it supplies phosphorus, calcium...
the biological environment, the formation of a layer of carbonated hydroxyapatite (CHA) initiates bonding to the bone tissues. The bioglass surface coating...
but a mixture of chondroitin sulfate and hydroxyapatite, the latter making up 70% of a bone. Hydroxyapatite is in turn composed of 39.8% of calcium, 41...
diameter in primates, enamel prism are tightly packed hydroxyapatite crystals structures. The hydroxyapatite crystals are hexagonal in shape, providing rigidity...
bone usually obtained from a bone bank), or synthetic (often made of hydroxyapatite or other naturally occurring and biocompatible substances) with similar...
component of bone is hydroxyapatite as well as amorphous forms of calcium phosphate, possibly including carbonate. Hydroxyapatite is the main component...
collagen) and two thirds mineral (calcium phosphate mostly in the form of hydroxyapatite) renders its diagenesis more complex. Alteration occurs at all scales...
and is incorporated into bones during the active mineralization of hydroxyapatite. When incorporated into bones, tetracycline can be identified using...
mineralized organic matrix. The primary inorganic component of human bone is hydroxyapatite, the dominant bone mineral, having the nominal composition of Ca10(PO4)6(OH)2...
surrounds the entire pulp. By volume, 45% of dentin consists of the mineral hydroxyapatite, 33% is organic material, and 22% is water. Yellow in appearance, it...
incorporate the material into its ultrastructure and form new bone. Hydroxyapatite is a biomaterial used to interface medical devices directly to bone...
digestive systems; is indispensable to the building of bone in the form of hydroxyapatite; and supports synthesis and function of blood cells. For example, it...
pseudogout, associated with periarticular or intra-articular deposition of hydroxyapatite or basic calcium phosphate (BCP) crystals. While primarily associated...
types of bisphosphonates. This chemical structure affords a high affinity for calcium hydroxyapatite, allowing for rapid and specific skeletal targeting....
drawn out from the hydroxyapatite. The mineral ions introduced during remineralisation restore the structure of the hydroxyapatite crystals. The clubbing...
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