Rastsvetaevite

Rastsveatevite is a rare mineral of the eudialyte group with the formula Na27K8Ca12Fe3Zr6Si4[Si3O9]4[Si9O27]4(O,OH,H2O)6Cl2. Its structure is modular.[2] It is only the third member of the group after andrianovite and davinciite with essential (site-dominating) potassium.[1] Potassium and sodium enter both N4 and M2 sites.[3] The mineral is named after Russian crystallographer Ramiza K. Rastsvetaeva.[1]

Rastsvetaevite
Tiny dark pink grains of rastsvetaevite in matrix. Field of view 3 mm. From: Rasvumchorr Mt, Khibiny Massif, Murmansk Oblast, Russia
General
CategorySilicate mineral, Cyclosilicate
Strunz classification9.CO.10
Dana classification64.1b.1.2
Crystal systemTrigonal
Crystal classDitrigonal pyramidal (3m)
H-M symbol: (3m)
Space groupR3m
Unit cella = 14.25, c = 60.97 [Å] (approximated); Z = 3
Identification
ColorReddish-pink
Crystal habitirregular grains
FractureConchoidal
TenacityBrittle
Mohs scale hardness5-6
LusterVitreous
StreakWhite
DiaphaneityTransparent
Specific gravity2.86
Optical propertiesUniaxial (+)
Refractive indexnω=1.60 nε = 1.60 (approximated)
References[1]

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.[1]

Notes on crystal structure

The c unit cell parameter in rastsvetaevite is doubled.[1]

gollark: How about it provides *one* advanced computer feature at a time but which one it is is randomly determined every bootup?
gollark: <@565075471012855820> What would "iron computers" do? Where do they fit between normal and advanced ones?
gollark: Ah, vaguely like my thing but actually functional, neat.
gollark: If it worked like actual furnaces, it should probably take less than 10 seconds.
gollark: https://osmarks.tk/skynet2/Also try the Skynet WebUI.

References

  1. Mindat, http://www.mindat.org/min-26586.html
  2. Khomyakov, A.P.; Nechelyustov, G.N.; Arakcheeva, A.V. (2006). "Rastsvetaevite, Na27K8Ca12Fe3Zr6Si4[Si3O9]4[Si9O27]4(O,OH,H2O)6Cl2, a new mineral with a modular eudialyte-like structure and crystal-chemical systematics of the eudialyte group". Proceedings of the Russian Mineralogical Society. 135 (1): 49–65.
  3. Johnsen, O.; Ferraris, G.; Gault, R. A.; Grice, J. D.; Kampf, A. R.; Pekov, I. V. (2003-06-01). "The nomenclature of eudialyte-group minerals". The Canadian Mineralogist. 41 (3): 785–794. doi:10.2113/gscanmin.41.3.785. ISSN 0008-4476.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.