Labyrinthite: Properties and Occurrences

Labyrinthite is a very rare mineral of the eudialyte group. When compared to other species in the group, its structure is extremely complex – with over 100 sites and about 800 cations and anions – hence its name. Its complexity being expressed in its formula: (Na,K,Sr)35Ca12Fe3Zr6TiSi51O144(O,OH,H2O)9Cl3. The formula is simplified as it does not show the presence of cyclic silicate groups.

General Information

  • Category: Silicate mineral, Cyclosilicate
  • Formula: (Na,K,Sr)35Ca12Fe3Zr6TiSi51O144(O,OH,H2O)9Cl3
  • Crystal system: Trigonal
  • Crystal class: Pyramidal (3) (same H-M symbol)


Complexity of the structure results in symmetry lowering from the typical centrosymmetrical group to R3 space group. Other eudialyte-group representatives with such symmetry lowering include aqualite, oneillite, raslakite, voronkovite. Labyrinthite is the second dual-nature representative of the group after dualite and third with essential titanium after dualite and alluaivite.

  • Color: Pink
  • Crystal habit: anhedral grains
  • Cleavage: None
  • Fracture: Conchoidal
  • Tenacity: Brittle
  • Mohs scale hardness: 5-6
  • Luster: Vitreous
  • Streak: White
  • Diaphaneity: Transparent
  • Density: 2.88 g/cm3 (measured)

Occurrence and association

Labyrinthite was discovered in hyperagpaitic (ultra-alkaline) pegmatite at Mt. Nyorkpakhk, Khibiny massif, Kola Peninsula, Russia, where it represents a late-stage mineral. It is a late-stage pegmatitic mineral in an alkaline igneous complex. It coexists with aegirine, alkaline amphibole, lamprophyllite, lomonosovite, potassium feldspar, pectolite, sodalite, and villiaumite.

Association: K-feldspar, sodalite, alkali amphiboles, aegirine, pectolite, lamprophyllite, lomonosovite, villiaumite, lovozerite-group minerals


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