Mineral Information and Data:

Brewsterite-Ba
Ba(Al2Si6)O16 • 5H2O [CNMNC approved formula]

Named as the barium analogue of brewterite-Sr. Named honoring Sir David Brewster (1781-1868), Scottish mineralogist. First published in 1993 as bariumbrewsterite and new name defined (IMA, 1997)

IMA status : Approved Species 1997 ()
CLASSIFICATION 
Dana
(8th edition) :
77.01.07.01a  (This Dana# Added)
  (77) Tectosilicate Zeolite group
  (77.01) true zeolites
  (77.01.07) Brewsterite and related species
  
Nickel-Strunz
(10th edition) :
09.GE.20
  (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: P21/m
Unit cell: a = 6.793(2)Å, b = 17.573(6)Å, c =7.759(2)Å; β = 94.54(3)° Z = 2
Crystal Habit: Crystals commonly equant or prismatic, striated and elongated along [100], to 1.5 cm. Platy, radial fibrous, and in granular aggregates.
Twinning: Lamellar || {010}
  
Color: White, colorless, yellowish, gray, greenish; colorless in thin section
Diaphaneity: Transparent
Luster: Vitreous to pearly on {010}
Hardness (Mohs): 5 - 5.5
Measured Density: 2.45 g/cm3
Cleavage: {010}, perfect
Tenacity: Brittle
Fracture: Uneven
Streak: White
  
Geologic Setting: Hydrothermally deposited in druses lining cavities in basalts and schists; more rarely in ore deposits.
Mineral Association: Zeolites, calcite, quartz
  
Synonyms/varieties: Bariumbrewsterite

 

Brewsterite-Ba
Colorless, translucent, stubby prismatic crystals 1 mm long
Origin: Strontian, Argyllshire, Scotland
Sample size: 5 x 5.5 x 4 cm
Photo: Tom Loomis

 

Brewsterite-Ba
(zoom-in of above)

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