Mineral Information and Data:

Ancylite-(Ce)
CeSr(CO3)2(OH) • H2O [CNMNC approved formula]

Named in 1899 for the composition and from the Greek "curved," in allusion to the rounded and distorted character of the crystals. Name changed from Ancylite to Ancylite-(Ce) in 1987.

IMA status : Approved Species 1987 ()
CLASSIFICATION 
Dana
(8th edition) :
16b.01.01.01  
  (16b) Carbonates - Hydroxyl or Halogen
  (16b.01) where (A)m (B)n (XO3)p Zq, with (m+n):p=1:1
  (16b.01.01) Ancylite group
  
Nickel-Strunz
(10th edition) :
05.DC.05
  (05) Carbonates and Nitrates
  (05.D) Carbonates with Additional Anions, with H2O
  (05.DC) With large cations
  
Crystal system: Orthorhombic System
Point group (H-M): mmm (or 2/m 2/m 2/m) — dipyramidal
Unit cell: a = 5.062 Å, b = 8.586 Å, c = 7.303 Å
Crystal Habit: Crystals stout to long prismatic, elongated along c-axis, minute pseudo-octahedral crystals with curved faces, grains
  
Color: Pale yellow-orange, pink, yellowish brown to brown, gray; colorless in transmitted light.
Diaphaneity: Transparent
Luster: Vitreous to dull on crystal faces, greasy on fracture surfaces
Hardness (Mohs): 4 - 4.5
Measured Density: 3.95 - 4.1 g/cm3
Tenacity: Tough
Fracture: Splintery
Streak: White
  
Geologic Setting: An uncommon accessory mineral in some nepheline syenites and carbonatites.
Mineral Association: Parisite-(Ce), synchysite-(Y), cordylite-(Ce), eudidymite, aegirine, microcline
  

 

Ancylite-(Ce)
Origin: Mont St. Hilaire, Quebec, Canada
Sample size: 1 x 1.5 x 1 cm, pinkish sheaf-like crystals to 5 mm
Photo: Tom Loomis

 

Ancylite-(Ce)
(zoom-in of above)

 

Ancylite-(Ce)
Light brown massive ancylite-(Ce) on aegirine, with catapleite
Origin: Mt. Aikuaivenchorr, Chibiny, Kola Peninsula, Russia
Sample size: 2 x 3.5 cm
Photo: Diederik Visser

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