Mineral Information and Data:

Ashcroftine-(Y)
K5Na5Y12Si28O70(OH)2(CO3)8 • 8H2O [CNMNC approved formula]

Named in 1993 to honor Frederick Noel Ashcroft (1878-1949), benefactor to the British Museum (Natural History), London, England. Renamed as Ashcroftine-(Y) 1987.

IMA status : Approved Species 1987 ()
CLASSIFICATION 
Dana
(8th edition) :
70.03.01.01  
  (70) Inosilicate Column or Tube Structures
  (70.03) with balo-silicates
  (70.03.01)
  
Nickel-Strunz
(10th edition) :
09.DN.15
  (09) Silicates
  (09.D) Inosilicates* Structural terminology per Liebau (1985)
  (09.DN) with 6-periodic double chains
  
Crystal system: Tetragonal System
Point group (H-M): 4/mmm (or 4/m 2/m 2/m) — ditetragonal-dipyramidal
Unit cell: a = 23.99Å, c = 17.51Å
Crystal Habit: As fibrous prismatic crystals, to 2 cm, striated parallel to [001]; in divergent sprays; as a fine, crystalline powder.
  
Color: Pale pink, white, pinkish brown, pinkish purple, deep violet-brown
Diaphaneity: Transparent to translucent
Luster: Vitreous, may be silky
Hardness (Mohs): 5
Measured Density: 2.61 g/cm3
Cleavage: Perfect on {100}, distinct on {001}
Tenacity: Flexible
Streak: White
  
Geologic Setting: In cavities in augite syenite (Narssarssuk, Greenland); in igneous breccia and pegmatites in an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada).
Mineral Association: Calcite, elpidite, albite, quartz, aegirine, orthoclase, zinnwaldite, graphite (Narssarssuk, Greenland); aegirine, bastnÄasite, lorenzenite, brookite, elpidite, leucosphenite, cordylite, narsarsukite (Mont Saint-Hilaire, Canada)
  

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