Mineral Information and Data:

Bastnasite-(Y)
YCO3F [CNMNC approved formula]

Named as the Y-predominant rare earth element in the bastnasite group. Group named after its locality: Bastnas Mine, Riddarhyttan district, Vastermanland, Sweden. Named per nomenclature of rare-earth minerals (IMA, 1966).

IMA status : Approved Species 1970 ()
CLASSIFICATION 
Dana
(8th edition) :
16a.01.01.03  
  (16a) Carbonates - Hydroxyl or Halogen
  (16a.01) in the Bastnasite/Shynchysite/Parasite Groups
  (16a.01.01) Bastnasite Subgroup
  
Nickel-Strunz
(10th edition) :
05.BD.20a
  (05) Carbonates and Nitrates
  (05.B) Carbonates with additional anions, without H2O
  (05.BD) With rare earth elements (REE)
  
Crystal system: Hexagonal System
Point group (H-M): 6m2 (or 6m2) — ditrigonal-dipyramidal
Space group: P6c2
Unit cell: a = 6.57(20) Å, c = 9.48(2) Å; Z = 6
Crystal Habit: Irregular grains, to 4 μm, aggregated into compact pseudomorphs after large gagarinite-(Y) crystals.
  
Color: Brick-red to carmine-red; pale brown in transmitted light.
Diaphaneity: Semi-transparent
Hardness (Mohs): 4 - 4.5
Measured Density: 3.9 – 4.0 g/cm3
  
Geologic Setting: A rare secondary mineral in a microcline–quartz pegmatite vein.
Mineral Association: Gagarinite-(Y), fluorite, microcline, hematite, quartz
  

 

Bastnasite-(Y)
Golden-brown bastnasite-(Y) psuedomorph after gagarinite-(Y) crystals
in quartz core of alkaline granitic pegmatite.
Origin: Verkhnee Espe Massif, Akzhaylyautas Mts, Kazakhstan.
Picture size: FOV ~12x10 mm
Photo and collection: © Pavel M. Kartashov

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