Serandite

Serandite
Serandite from Mont Saint-Hilaire, Quebec, Canada
General
CategoryInosilicates
Formula
(repeating unit)
Na(Mn2+,Ca)2Si3O8(OH)
IMA symbolSrd[1]
Strunz classification9.DG.05
Dana classification65.2.1.5
Crystal systemTriclinic
Crystal classPinacoidal (1)
(same H-M symbol)
Space groupP1
Unit cella = 7.683(1) Å, b = 6.889(1) Å
c = 6.747(1) Å, α = 90.53(5)°
β = 94.12(2)°, γ = 102.75(2)°
Z = 2
Identification
Coloursalmon pink to orange
TwinningAround [010] composition plane {100}, less commonly contact twin on {110}
CleavagePerfect on {001} and {100}
FractureIrregular, uneven
TenacityBrittle
Mohs scale hardness5 to 5.5
LusterVitreous to greasy; fibrous aggregates are dull to silky[2]
StreakWhite
DiaphaneityTransparent, Translucent
Density3.34 g/cm3 (measured)
Optical propertiesBiaxial (+)
Refractive indexnα = 1.668
nβ = 1.671
nγ = 1.703
Birefringenceδ = 0.035
2V angle39°
Dispersionr < v moderate
References[3]

Serandite[4] is a mineral with formula Na(Mn2+,Ca)2Si3O8(OH). The mineral was discovered in Guinea in 1931 and named for J. M. Sérand. Serandite is generally red, brown, black or colorless. The correct name lacks an accent.[5]

  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. ^ "Sérandite" (PDF). Handbook of Mineralogy. Mineral Data Publishing. Archived from the original (PDF) on September 11, 2021. Retrieved July 11, 2012.
  3. ^ "Sérandite". Mindat. Retrieved July 11, 2012.
  4. ^ "Serandite". Webmineral. Retrieved July 25, 2012.
  5. ^ Hålenius, U., Hatert, F., Pasero, M., and Mills, S.J., IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) Newsletter 28. Mineralogical Magazine 79(7), 1859–1864

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