Mineral Information and Data:

Erionite-Ca
Ca5(Si26Al10)O72 • 28H2O [CNMNC approved formula]

Named as the calcium-dominant phase of the erionite series. Species name come from the Greek for wool, in allusion to its white, fibrous, wool-like appearance. Defined per nomenclature for zeolite minerals (IMA, 1997).

IMA status : Approved Species 1997 ()
CLASSIFICATION 
Dana
(8th edition) :
77.01.02.05b  (This Dana# Added)
  (77) Tectosilicate Zeolite group
  (77.01) true zeolites
  (77.01.02) Chabazite and related species
  
Nickel-Strunz
(10th edition) :
09.GD.20
  (09) Silicates
  (09.G) Tektosilicates with Zeolitic H2O
  (09.GD) Chains of 6-membered rings - tabular zeolites
  
Crystal system: Hexagonal System
Point group (H-M): 6/mmm (or 6/m 2/m 2/m) — dihexagonal-dipyramidal
Unit cell: a = 13.333Å, c = 15.091Å , Z=1
Crystal Habit: Crystals accicular.
  
Color: White, Green, Gray, Orange
Diaphaneity: Transparent to translucent
Luster: Vitreous
Hardness (Mohs): 3.5 - 4
Measured Density: 2.09 - 2.13 g/cm3
Fracture: Splintery
Streak: White
  
Geologic Setting: Occurs in volcanic and sedimentary rocks. Found in amygdules in altered basalt.
  
Comments: A zeolite difficult to distinguish from offretite.

 

Erionite-Ca
Radiating white crystals with clinoptilolite.
Mineral identification confirmed by single-crystal X-ray diffraction and chemical analysis only.
Origin: Maze, Niigata Prefecture, Japan
Photo: © RRUFF Project

 

Erionite-Ca
(zoom-in of above)

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