Portlandite

Portlandite
Portlandite and ettringite
General
CategoryOxide mineral
Formula
(repeating unit)
Ca(OH)2
IMA symbolPor[1]
Strunz classification4.FE.05
Dana classification06.02.01.04
Brucite group
Crystal systemTrigonal
Crystal classHexagonal scalenohedral (3m)
H-M symbol: (3 2/m)
Space groupP3m1
Unit cella = 3.589 Å, c = 4.911 Å; Z = 1
Identification
ColorColorless, white to greenish white
Crystal habitHexagonal plates; commonly fibrous, powdery, massive.
CleavagePerfect on {0001}
TenacitySectile with flexible cleavage plates
Mohs scale hardness2
LusterPearly on cleavages
DiaphaneityTransparent
Specific gravity2.23
Optical propertiesUniaxial (−)
Refractive indexnω = 1.574 nε = 1.547
Birefringenceδ = 0.027
SolubilitySoluble in water producing an alkaline solution
Alters toAlters to CaCO3 on exposure to CO2 bearing waters
References[2][3][4][5][6]

Portlandite is a hydroxide-bearing mineral typically included in the oxide mineral class. It is the naturally occurring form of calcium hydroxide (Ca(OH)2) and the calcium analogue of brucite (Mg(OH)2).

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ "Mineralienatlas - Fossilienatlas". www.mineralienatlas.de.
  3. ^ "Handbook of Mineralogy" (PDF).
  4. ^ "Portlandite: Mineral information, data and localities". www.mindat.org.
  5. ^ "Portlandite Mineral Data". www.webmineral.com.
  6. ^ Pallache, Charles; Berman, Harry; Frondel, Clifford (1944). The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana (7 ed.). Wiley. pp. 641–642. ISBN 9780471192398.