Mineral Information and Data:

Afghanite
Na22Ca10(Si24Al24)O96(SO4)6Cl6 [CNMNC approved formula]

Named for the country of first occurrence, AFGHANistan.

IMA status : Approved Species 1967 (IMA1967-041)
CLASSIFICATION 
Dana
(8th edition) :
76.02.05.01  
  (76) Tectosilicate Al-Si Framework
  (76.02) Feldspathoids and related species
  (76.02.05) Cancrinite group
  
Nickel-Strunz
(10th edition) :
09.FB.05
  (09) Silicates
  (09.F) Tektosilicates without Zeolitic H2O
  (09.FB) Tektosilicates with additional anions
  
Crystal system: Hexagonal System
Point group (H-M): 6mm — dihexagonal-pyramidal
Unit cell: a = 12.77Å, c = 21.35Å
Crystal Habit: As stout to slender, thin tabular laths and as rounded grains.
Twinning: Perfect on {1010}
  
Color: Blue, colorless
Diaphaneity: Transparent
Luster: Vitreous
Hardness (Mohs): 5.5 - 6
Measured Density: 2.55 g/cm3
Cleavage: Perfect
Tenacity: Brittle
Fracture: Conchoidal
Streak: White
  
Geologic Setting: In thin veinlets cutting lazurite crystals (Sar-e-Sang, Afghanistan); in silicified limestone xenoliths in pumice (Pitigliano quarry, Italy)
Mineral Association: Lazurite, sodalite, nepheline, phlogopite, olivine, diopside, vesuvianite, calcite, pyrite
  
Comments: Cancrinite group.

 

Afghanite
Origin: Pitigliano quarry, Grosseto Prov., Tuscany, Italy
Sample size: 4 x 3 x 3 cm, crystal 1 mm
Photo: Tom Loomis

 

Afghanite
(zoom-in of above)

 

Afghanite
Origin: Lapis-lazuli Mine, Sar-e-Sang, Badakhshan (Badakshan; Badahsan) Province, Afghanistan
Sample size: 8.7 x 3.6 x 3.9 cm
Photo: Dan Weinrich

 

Afghanite
(zoom-in of above)

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