Mineral Information and Data:

Mesolite
Na2Ca2(Si9Al6)O30 • 8H2O [CNMNC approved formula]

Named from the Greek mesos - "middle", alluding to its composition intermediate between natrolite and scolecite. Originally published in 1816. Approved and defined per nomenclature for zeolite minerals (IMA, 1997).

IMA status : Approved Species 1997 ()
CLASSIFICATION 
Dana
(8th edition) :
77.01.05.04  
  (77) Tectosilicate Zeolite group
  (77.01) true zeolites
  (77.01.05) Natrolite and related species
  
Nickel-Strunz
(10th edition) :
09.GA.05
  (09) Silicates
  (09.G) Tektosilicates with Zeolitic H2O
  (09.GA) Zeolites with T5O10 Units - The Fibrous Zeolites
  
Crystal system: Orthorhombic System
Point group (H-M): mm2 — pyramidal
Space group: Fdd2
Unit cell: a =18.4049(8) Å, b = 56.655(6) Å, c = 6.5443(4) Å, Z=8
Crystal Habit: As prismatic crystals, elongated || [001], to 20 cm; commonly in hairlike tufts and aggregates of fibers; divergent, radiating compact masses; in fibrous stalactites; porcelaneous, massive.
Twinning: Characteristically twinned on {010} or {100}.
  
Color: Colorless, white, gray, yellowish; in thin section, colorless.
Diaphaneity: Transparent to translucent, opaque
Luster: Vitreous, silky when fibrous
Hardness (Mohs): 5
Measured Density: 2.26 g/cm3
Cleavage: {110}, {110}, perfect
Tenacity: Brittle, but compact masses are tough
Fracture: Uneven
  
Geologic Setting: In cavities of volcanic rocks, typically basalt, also in andesites, porphyries, and hydrothermal veins.
Mineral Association: Natrolite, scolecite, other zeolites, calcite
  
Other Properties: Piezoelectric. Pyroelectric.
Comments: May exhibit only a small pyroelectric effect.

 

Mesolite
Mesolite on celestine
Origin: Cheyenne, Laramy Co., Wyoming, U.S.A.
Sample size: Microscopic image
Photo and Owner: Lou Perloff

 

Mesolite
Origin: near Poona, Maharashtra State, India
Sample size: 16 x 14 x 10 cm
Photo: Dan Weinrich

 

Mesolite
(zoom-in of above)

 

Mesolite
Origin: Ritter Hot Springs, Ritter, Grant Co., Oregon, U.S.A.
Sample size: 5.8 x 4.2 x 3.6 cm
Photo: Dan Weinrich

 

Mesolite
(zoom-in of above)

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