Article · Wikipedia archive · Last revised Jun 8, 2026

Calcium hydroxyphosphate

Calcium hydroxyphosphate (calcium phosphate tribasic, tribasic calcium phosphate, hydroxyapatite, HAp) is an inorganic chemical compound that is made up of calcium, hydrogen, oxygen and phosphorus. Its formula is Ca5(OH)(PO4)3.

Last revised
Jun 8, 2026
Read time
≈ 1 min
Length
140 w
Citations
1
Source
Wikipedia ↗
Calcium hydroxyphosphate
Names
IUPAC name
pentacalcium hydroxide triphosphate
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.013.769
EC Number
  • 235-330-6
UNII
  • InChI=1S/5Ca.3H3O4P.H2O/c;;;;;3*1-5(2,3)4;/h;;;;;3*(H3,1,2,3,4);1H2/q5*+2;;;;/p-10
    Key: XYJRXVWERLGGKC-UHFFFAOYSA-D
  • [OH-].[O-]P(=O)([O-])[O-].[O-]P(=O)([O-])[O-].[O-]P(=O)([O-])[O-].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2]
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H315, H319, H335
P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Calcium hydroxyphosphate (calcium phosphate tribasic, tribasic calcium phosphate, hydroxyapatite, HAp) is an inorganic chemical compound that is made up of calcium, hydrogen, oxygen and phosphorus. Its formula is Ca5(OH)(PO4)3.1

It is found in the body and as the mineral hydroxyapatite.

References

References