Voronkovite

Voronkovite is a very rare mineral of the eudialyte group with the formula Na15(Na, Ca, Ce)3(Mn, Ca)3Fe3Zr3Si2Si24O72(OH, O)4Cl·H2O. It is a trigonal-pyramidal yellowish-brown mineral containing calcium, chlorine, hydrogen, iron, manganese, niobium, oxygen, silicon, sodium, and zirconium.

The formula is based on the simplified original one; it does not show the presence of cyclic silicate groups. The type material is deposited at the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.

General Information

  • Category: Silicate mineral, Cyclosilicate
  • Formula: Na15(Na,Ca,Ce)3(Mn,Ca)3Fe3Zr3Si2Si24O72(OH,O)4Cl·H2O
  • Crystal system: Trigonal
  • Crystal class: Pyramidal (3)

Properties

Voronkovite has lowered symmetry (space group R3, instead of more specific for the group R3m one), similarly to some other eudialyte-group members: aqualite, labyrinthite, oneillite and raslakite. The specific feature of voronkovite is, among others, strong enrichment in sodium.

  • Color: Light brown
  • Crystal habit: Rounded crystals
  • Fracture: Conchoidal
  • Tenacity: Brittle
  • Mohs scale hardness: 5
  • Luster: Vitreous
  • Streak: White
  • Diaphaneity: Transparent
  • Density: 2.95 g/cm3 (calculated)
  • Optical properties: Uniaxial (+)

Occurrence and association

Voronkovite comes from an ultra-alkaline pegmatite of Mt. Alluaiv, Lovozero massif, Kola Peninsula, Russia. It associates with aegirine, lomonosovite, manganoneptunite, microcline, nepheline, shkatulkalite, sodalite, terskite, sphalerite, and vuonnemite.

The mineral is associated with microcline, sodalite, nepheline, aegirine, terskite, lomonosovite, vuonnemite, shkatulkalite, manganoneptunite, and sphalerite.

 

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