Mineral Information and Data:

Apophyllite-(KOH)
KCa4Si8O20(OH,F) • 8H2O [CNMNC approved formula]

Named from the Greek apophylliso - "it flakes off" and the predominant hydroxyl anion.

IMA status : Renamed IMA Approved; 2008 (IMA1976-1)
CLASSIFICATION 
Dana
(8th edition) :
72.03.01.02  
  (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 = 8.97Å, c = 15.83Å
Crystal Habit: Crystalline; Massive ; Pseudo Cubic
  
Color: White, Pink, Green, Yellow, Violet
Diaphaneity: Transparent
Luster: Vitreous
Hardness (Mohs): 4 - 5
Measured Density: 2.3 - 2.4 g/cm3
Cleavage: 1; {001} Perfect
Streak: White
  
  
Synonyms/varieties: Hydroxyapophyllite
Comments: IMA approved 1976 as Hydroxyapophyllite. Renamed to Apophyllite-(KOH) in 2008.

 

Apophyllite-(KOH)
Crystal cluster of tabular Apophyllite-(KOH).
Origin: Wessels Mine, Kalahari Manganese Field, Northern Cape Province, South Africa.
Sample size: 2.5 x 2.3 cm
Photo: John Veevaert, Trinity Mineral Co

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