Mineral Information and Data:

Stilbite-Ca
NaCa4(Si27Al9)O72 • 28H2O [CNMNC approved formula]

Named as the calcium-dominant phase of the stilbite series. Species named from the Greek stilbe - "luster" in allusion to its pearly to vitreous luster. First published in 1801. Name changed per nomenclature for zeolite minerals (IMA, 1997).

IMA status : Renamed IMA Approved; 1997 ()
CLASSIFICATION 
Dana
(8th edition) :
77.01.04.03  
  (77) Tectosilicate Zeolite group
  (77.01) true zeolites
  (77.01.04) Heulandite and related species
  
Nickel-Strunz
(10th edition) :
09.GE.10
  (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: P2/m
Unit cell: a = 13.68 Å, b = 18.13 Å, c = 11.30 Å, b = 129.1°
Crystal Habit: Crystals typically thin tabular, flattened on [010], to 14 cm; in fasicled, sheaf-like, or globular aggregates
Twinning: Universal on {001} penetration, cruciform
  
Color: White, yellowish, gray, pink, reddish, orange, light brown to dark brown
Diaphaneity: Transparent, Translucent
Luster: Vitreous, pearly on cleavage
Hardness (Mohs): 3.5 to 4
Measured Density: 2.09 to 2.20 g/cm3
Cleavage: 2; {010} perfect, {100} distinct
Tenacity: Brittle
Fracture: Uneven
Streak: White
  
Geologic Setting: A low-temperature hydrothermal mineral, in amygdules and cavities in basalts, andesites, and various metamorphic rocks. Formed in hot springs deposits, and as a cementing agent in some sandstones and conglomerates.
Mineral Association: Zeolites, prehnite, calcite, quartz
  
Synonyms/varieties: Desmine, epidesmine

 

Stilbite-Ca
Nice, pink 1.5 cm "bowtie" habit crystal with a 1.5 cm calcite crystal
Origin: King's Valley, Benton Co., Oregon, U.S.A.
Sample size: 4 x 4 x 3 cm
Photo: Tom Loomis

 

Stilbite-Ca
(zoom-in of above)

 

Stilbite-Ca
Stilbite on quartz stalactite
Origin: Jalgaon, Maharashtra, India
Sample size: 13 x 6 x 4 cm
Photo: Rob Lavinsky

 

Stilbite-Ca
(zoom-in of above)

 

Stilbite-Ca
Stilbite with calcite, apophyllite and heulandite
Origin: Appalachian Stone Quarry, Haverstran, Rockland Co., New York, United States
Sample size: 7 x 4 x 2.5 cm
Photo: Tom Loomis

 

Stilbite-Ca
(zoom-in of above)

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