Mineral Information and Data:

Apophyllite-(KF)
KCa4Si8O20F • 8H2O [CNMNC approved formula]

Named from the Greek apophylliso - "it flakes off." and the composition containing fluorine;.

IMA status : Renamed IMA Approved; 2008 (IMA1976-001)
CLASSIFICATION 
Dana
(8th edition) :
72.03.01.01  
  (72) Phyllosilicate Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings
  (72.03) with 3-, 4-, or 5-membered rings and 8-membered rings
  (72.03.01) Apophyllite group (4- & 8-membered rings)
  
Nickel-Strunz
(10th edition) :
09.EA.15
  (09) Silicates
  (09.E) Phyllosilicates
  (09.EA) Single nets of tetrahedra with 4-, 5-, (6-), and 8-membered rings
  
Crystal system: Tetragonal System
Point group (H-M): 4/mmm (or 4/m 2/m 2/m) — ditetragonal-dipyramidal
Unit cell: a = 8.963(2) Å, c = 15.804(2) Å
Crystal Habit: Crystalline; Massive ; Pseudo Cubic
  
Color: Colorless, pale green, aquamarine, white, pink, yellow
Diaphaneity: Transparent, Translucent
Luster: Vitreous, Pearly
Hardness (Mohs): 4.5 - 5
Measured Density: 2.33 - 2.37 g/cm3
Cleavage: 2; Perfect on {001}, Imperfect on {110}
Tenacity: Brittle
Fracture: Irregular/Uneven
Streak: White
  
Geologic Setting: A secondary mineral in amygdules or druses in basalts. A late-stage mineral in some mineral deposits.
  
Synonyms/varieties: Fluorapophyllite
Other Properties: Gemstone Extremely Rare.
Comments: IMA approved 1976 as Fluorapophyllite. Renamed to Apophyllite-(KF) in 2008.

 

Apophyllite-(KF)
Doubly terminated, very clear and perfect Apophyllite-(KF) with white stilbite.
Origin: Jalgaon, India.
Sample size: 4 x 3.5 cm
Photo: © Fabre Minerals

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