Rastsveatevite

Rastsveatevite is a rare mineral of the eudialyte group with the formula Na27K8Ca12Fe3Zr6Si4[Si3O9]4[Si9O27]4(O, OH, H2O)6Cl2. It is a trigonal-ditrigonal pyramidal pink mineral containing calcium, chlorine, hydrogen, iron, oxygen, potassium, silicon, sodium, and zirconium. Its structure is modular.

General Information

  • Category: Silicate mineral, Cyclosilicate
  • Formula: Na27K8Ca12Fe3Zr6Si4[Si3O9]4[Si9O27]4(O,OH,H2O)6Cl2
  • Crystal system: Trigonal
  • Crystal class: Ditrigonal pyramidal (3m)

Properties

It is only the third member of the group after andrianovite and davinciite with essential (site-dominating) potassium. Potassium and sodium enter both N4 and M2 sites. The mineral is named after Russian crystallographer Ramiza K. Rastsvetaeva.

  • Color: Reddish-pink
  • Crystal habit: irregular grains
  • Fracture: Conchoidal
  • Tenacity: Brittle
  • Mohs scale hardness: 5-6
  • Luster: Vitreous
  • Streak: White
  • Diaphaneity: Transparent
  • Density: 2.86 g/cm3 (measured)
  • Optical properties: Uniaxial (+)

Occurrence and association

Rastsvetaevite was originally found in hyperagpaitic (ultra-alkaline) pegmatite at Mt. Rasvumchorr, Khibiny massif, Kola Peninsula, Russia. Associated minerals are aegirine, nacaphite, nepheline, natrite, schcherbakovite, sodalite, villiaumite, and rasvumite.

 

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