Mineral Information and Data:

Heulandite-K
KCa4(Si27Al9)O72 • 24H2O [CNMNC approved formula]

Named as the potassium-dominant phase of the heulandite series. Species named after the English mineral collector, John Henry Heuland (1778-1856), a British mineral collector and dealer. Named per nomenclature for zeolite minerals (IMA, 1997).

IMA status : Approved Species 1997 ()
CLASSIFICATION 
Dana
(8th edition) :
77.01.04.01b  (This Dana# Added)
  (77) Tectosilicate Zeolite group
  (77.01) true zeolites
  (77.01.04) Heulandite and related species
  
Nickel-Strunz
(10th edition) :
09.GE.05
  (09) Silicates
  (09.G) Tektosilicates with Zeolitic H2O
  (09.GE) Chains of T10O20 Tetrahedra
  
Crystal system: Monoclinic System
Point group (H-M): 2/m — prismatic
Space group: B2/m
Unit cell: a = 7.46Å, b = 17.84Å, c = 15.88Å, Z=2
  
Color: White, Colorless, Red, Yellow, Brown, Green
Diaphaneity: Transparent
Luster: Vitreous, Pearly
Hardness (Mohs): 3 -3.5
Cleavage: Perfect on the {010}
Tenacity: Brittle
Streak: White
  
  

 

Heulandite-K
Coating of orange grains.
Origin: Albero Bassi, Vicenza, Veneto, Italy.
Photo: © RRUFF Project

 

Heulandite-K
(zoom-in of above)

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