Manganoeudialyte
Pink crystals and aggregates of the rare mineral manganoeudialyte (IMA 2009-039) from the type locality (Pedra Balao, Pocos de Caldas, Minas Gerais, Brazil).
General
CategoryCyclosilicates
Formula
(repeating unit)
Na14Ca6Mn3Zr3[Si26O72(OH)2]Cl2·4H2O
IMA symbolMeud[1]
Crystal systemTrigonal
Crystal classDitrigonal pyramidal (3m)
(same H-M symbol)
Space groupR3m
Unit cella = 14.25, c = 30.08 [Å]
(approximated); Z = 3
Identification
ColorPink to purple
Crystal habitinterstitial patches
CleavageNone
FractureUneven
TenacityBrittle
Mohs scale hardness5-6
LusterVitreous
StreakWhite
DiaphaneityTransparent or translucent
Specific gravity2.89-2.94 (measured)
Optical propertiesUniaxial (+)
Refractive indexnω=1.60 nε=1.61 (approximated)
PleochroismNone
References[2][3][4]

Manganoeudialyte is an moderately rare mineral of the eudialyte group,[2] with formula Na14Ca6Mn3Zr3Si2[Si24O72(OH)2]Cl2·4H2O. The formula given is one of the forms that can be given, based on the originally reported one, and shows dominance of silicon at both the M3 and M4 sites. As suggested by its name, it is the manganese-analogue of eudialyte.[3][5]

Occurrence and association

Manganoeudialyte was discovered in khibinites of the Poços de Caldas massif, Brazil.[3] Associated minerals are aegirine, analcime, astrophyllite, cancrinite, fluorite, lamprophyllite, nepheline, potassium feldspar, rinkite, sodalite, and titanite.[2]

Notes on chemistry

Impurities in manganoeudialyte include strontium, potassium, niobium, aluminium, fluorine, and minor hafnium, cerium, and lanthanum.[2][3]

References

  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. 1 2 3 4 Mindat, Manganoeudialyte, http://www.mindat.org/min-39640.html
  3. 1 2 3 4 Nomura, S.F., Atencio, D., Chukanov, N.V., Rastsvetaeva, R.K., Coutinho, J.M.V., and Karipidis, T.K., 2010: Manganoeudialyte - a new mineral from Poços de Caldas, Minas Gerais, Brasil. Zapisko RMO 4
  4. Mineralienatlas
  5. Handbook of Mineralogy, Manganoeudialyte, http://www.handbookofmineralogy.org/pdfs/manganoeudialyte.pdf


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