Aqualite

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Aqualite
General
CategorySilicate mineral, Cyclosilicate
Formula
(repeating unit)
(H3O)8(Na,K,Sr)5Ca6Zr3Si26O66)(OH)9Cl
IMA symbolAq[1]
Strunz classification9.CO.10
Crystal systemTrigonal
Crystal classPyramidal (3)
H-M symbol: (3)
Space groupR3
Unit cella = 14.08, c = 31.24 [Å] (approximated); Z = 3
Identification
ColorPink (pale)
Crystal habitidiomorphic crystals (max. 3 cm)
CleavageNone
FractureConchoidal
Mohs scale hardness4–5
LusterVitreous
StreakWhite
DiaphaneityTranslucent
Density2.58 (measured), 2.66 (calculated)
Optical propertiesUniaxial (+)
Refractive indexnω = 1.57, nε = 1.57 (approximated)
PleochroismColorless to pink (W), pink (E)
Ultraviolet fluorescencedull yellow (weak)
References[2][3]

Aqualite is a very rare mineral of the eudialyte group, with formula (H3O)8(Na,K,Sr)5Ca6Zr3SiSi(Si24O66)(OH)9Cl.[2][3] The formula given does not show the presence of cyclic silicate groups. The original formula was extended to show the presence of silicon at both M3 and M4 sites, according to the nomenclature of the eudialyte group.[4] Aqualite is unique among the eudialyte group in being hydronium-rich (the only other eudialyte-group species with essential hydronium, is the recently discovered ilyukhinite).[2] Among the other representatives of the group it also distinguish in splitting of the M1 site into two sub-sites, both occupied by calcium. Thus, its symmetry is lowered from typical for most eudialytes R3m (or R-3m) to R3. The name refers to high content of water in the mineral.[3][4]

Notes on Chemistry[edit]

Elements occurring as admixtures in aqualite include barium, iron, rare-earth elements (including cerium), titanium, aluminium and trace niobium.[3]

Occurrence and association[edit]

Aqualite was discovered among peralkaline pegmatites of the Inagli massif, Sakha-Yakutia, Russia. Associated minerals are aegirine, batisite, eckermanite, innelite, lorezenite, natrolite, microcline, thorite, and galena.[3]

Origin[edit]

Aqualite is thought to be formed by ion exchange transformation of a precursor mineral.[3]

References[edit]

  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. ^ a b c "Aqualite: Aqualite mineral information and data". Mindat.org. Retrieved 2016-03-08.
  3. ^ a b c d e f Khomyakov, A. P., Nechelyustov, G. N., and Rastsvetaeva, R. K., 2007: Aqualite, a new mineral species of the eudialyte group from the Inagli alkaline pluton, Sakha-Yakutia, Russia, and the problem of oxonium in hydrated eudialytes. Geology of Ore Deposits 49(8), 739–751.
  4. ^ a b Johnsen, O., Ferraris, G., Gault, R. A., Grice, D. G., Kampf, A. R., and Pekov, I. V., 2003. The nomenclature of eudialyte-group minerals. The Canadian Mineralogist 41, 785–794.