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Sérandite from Mont Saint-Hilaire, Quebec, Canada
Category Inosilicates
(repeating unit)
Strunz classification 9.DG.05
Dana classification
Crystal symmetry Pinacoidal
H-M symbol: 1
Space group: P1
Unit cell a = 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
Crystal system Triclinic
Twinning Around [010] composition plane {100}, less commonly contact twin on {110}
Cleavage Perfect on {001} and {100}
Fracture Irregular, uneven
Tenacity Brittle
Mohs scale hardness 5 to 5.5
Luster Vitreous to greasy; fibrous aggregates are dull to silky[1]
Streak White
Diaphaneity Transparent, Translucent
Density 3.34 g/cm3 (measured)
Optical properties Biaxial (+)
Refractive index nα = 1.668
nβ = 1.671
nγ = 1.703
Birefringence δ = 0.035
2V angle 39°
Dispersion r < v moderate
References [2]

Sérandite, also serandite,[3] is a mineral with formula Na(Mn2+,Ca)2Si3O8(OH). The mineral was discovered in Guinea in 1931 and named for J. M. Sérand. Sérandite is generally red, brown, black or colorless.


Sérandite is transparent to translucent and is normally salmon-pink, light pink, rose-red, orange, brown, black, or colorless; in thin section, it is colorless.[1] Octahedrally bonded Mn(II) is the primary contributor to the mineral's pink colors.[4]

Crystals of the mineral can be prismatic to acicular and elongated along [010], bladed, blocky, or tabular and flattened on {100}, occur as a radiating aggregate, or have massive habit.[1] Sérandite is a member of the wollastonite group and is the manganese analogue of pectolite.[2]


Sérandite was discovered on Rouma Island, part of the Los Islands in Guinea.[2] The mineral was described by À. Lacroix in the journal Comptes Rendus hebdomadaires des séances de l’Académie des Sciences.[5] He named it sérandite in honor of J.M. Sérand, a mineral collector who helped in the collection of the mineral.[2]

Occurrence and distribution[edit]

Sérandite has been found in Australia, Brazil, Canada, Guinea, Italy, Japan, Namibia, Norway, Russia, South Africa, and the United States.[2] The type material is held at the National Museum of Natural History in Washington, D.C.[1]

At Mont Saint-Hilaire, Quebec, sérandite occurs in sodalite xenoliths and pegmatites cutting syenites within an intrusive alkalic gabbro-syenite complex. In Point of Rocks, New Mexico, it occurs in vugs in phonolite. At the Tumannoe deposit in Russia, sérandite occurs in a manganese rich deposit associated with volcanic rocks and terrigenous (non-marine) sediments which has been altered by contact metamorphism.[1]

Sérandite has been found in association with aegirine, analcime, arfvedsonite, astrophyllite, eudialyte, fluorite, leucophanite, mangan-neptunite, microcline, nepheline, sodalite, and villiaumite.[1]


  1. ^ a b c d e f "Sérandite" (PDF). Handbook of Mineralogy. Mineral Data Publishing. Retrieved July 11, 2012. 
  2. ^ a b c d e "Sérandite". Mindat. Retrieved July 11, 2012. 
  3. ^ "Serandite". Webmineral. Retrieved July 25, 2012. 
  4. ^ Manning, p. 357.
  5. ^ Lacroix, p. 189.


Further reading[edit]

External links[edit]

Media related to sérandite at Wikimedia Commons