Mineral Information and Data:

Armenite
BaCa2(Si9Al6)O30 • 2H2O [CNMNC approved formula]

Named after its locality: Armen Mine, Kongsberg, Norway.

IMA status : Valid species (Pre-IMA 1939) Grandfathered
CLASSIFICATION 
Dana
(8th edition) :
63.02.01b.01  
  (63) Cyclosilicate Condensed Rings
  (63.02) 6-membered rings
  (63.02.01b) Milarite - Osumilite group
  
Nickel-Strunz
(10th edition) :
09.CM.05
  (09) Silicates
  (09.C) Cyclosilicates
  (09.CM) [Si6O18]12- 6-membered double rings (sechser-Doppelringe)
  
Crystal system: Orthorhombic System
Point group (H-M): mm2 — pyramidal
Unit cell: a = 13.87 Å, b = 18.66 Å, c = 10.70 Å
Crystal Habit: Sheaves of prismatic crystals, with individuals to 2.5 cm.
Twinning: complex, showing sectored triplets, may be lamellar
  
Color: Grayish green, colorless
Diaphaneity: Translucent
Luster: Vitreous
Hardness (Mohs): 7 - 8
Measured Density: 2.75 g/cm3
Cleavage: 2; {010} perfect, {110} distinct
Tenacity: Brittle
Streak: White
  
Geologic Setting: In calcite veins (Kongsberg, Norway); in manganese-metasomatized diorite included in later granodiorite (Remigny, Canada).
Mineral Association: Axinite, pyrrhotite, quartz (Kongsberg, Norway); albite, manganiferous zoisite, piemontite, prehnite, epidote, muscovite (Remigny, Canada); celsian, bytownite (Broken Hill, Australia)
  
Other Properties: Gemstone Extremely Rare.

 

Armenite
Origin: Simplon Pass, Brig, Valais, Switzerland
Sample size: Microscopic image
Photo and Owner: Lou Perloff

 

Armenite
Origin: Simplon Pass, Wasen Alps, Valais, Switzerland
Sample size: 3.2 x 2.2 x 1.5 cm
Photo: Rob Lavinsky

 

Armenite
(zoom-in of above)

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