Zeolite gallery
Analcime
Formula: Na16[Al16Si32O96] ·16 H2O
Symmetry: cubic; tetragonal, orthorhombic, or monoclinic
Habitus: crystals commonly trapezohedra {211}
granular, compact massive, typically showing concentzric structure
Cleavage very poor on {100}
Fracture subconcoidal
Hardness 5 - 5.5
Density 2.24 - 2.29
Name from the greek for weak, alluding to the weak electrostatic charge developed when heated or rubbed




Analcime from the Hvalfjördur area, Iceland.
Image width: 20 mm		 Analcime from the Hvalfjördur area, Iceland.
Image width: 5 mm

up


Chabazite
Formula: (Ca0.5,Na,K)4[Al4Si8O24] ·12 H2O
Symmetry: triclinic, pseudohexagonal
Habitus: tabular, complex to rounded twinne forms, anhedral, garnular, or massive
Twinning: interpenetrant, simple and repeated
Cleavage {1011} distinct
Fracture uneven
Hardness 4 - 5
Density 2.05 - 2.20
Name from the Greek chabazios, an ancient of a stone

Chabazite together with thomsonite from the Hvalfjördur area, Iceland.
Image width: 35 mm		 Chabazite together with thomsonite from the Hvalfjördur area, Iceland.
Image width: 20 mm

up

Epistilbite

Formula: Ca3[Al6Si18O48] ·16 H2O
Symmetry: monolcinic
Habitus: crastyls prismatic, in spherulitic or sheaflike aggregates
Twinning: always on (100), to form penetration crosses
Cleavage {101} perfect
Fracture uneven
Hardness 4
Density 2.22 - 2.28
Name from the Greek epi for near, and the quite similar mineral stilbite
Epistilbite from the Hvalfjördur area, Iceland.
Image width: 20 mm

up

Faujasite
Formula: (Na,K,Ca0.5)7[Al7Si29O72] ·22 H2O
Symmetry: monolcinic
Habitus: crystals octahedra or rarely trisoctahedra
twinning on {111}, contact and penetration twins
Cleavage {111} perfect
Fracture uneven to conchoidal
Hardness 4.5 - 5
Density 1.92 - 1.93
Name Honoring Barthélemy Faujas de Saint Fond (1741-1819), French mineralogist and vulcanologist

Faujasite with phillipsite and offretite from Limberg/Sasbach, Kaiserstuhl/Germany.
Image width: 0.7 mm

up
Heulandite

Formula: (Na,K,Ca0.5,Mg0.5)56[Al56Si136O384] ·235 H2O
Symmetry: cubic
Habitus: crystals commonly tabula || {010}, and elongated, widest at the centre, hence called "coffin-shaped"; also granular to massive
Cleavage {010} perfect
Fracture subconcoidal to uneven
Hardness 3.5 - 4
Density 2.10 - 2.20
Name for the English mineral collector and dealer John Henry Heuland (1778-1856)
Heulandite from the Hvalfjördur area, Iceland.
Image width: 7 mm

up

Laumontite

Formula: Ca4[Al8Si16O48] ·16 H2O
Symmetry: monoclinic
Habitus: crystals square prisms with steep oblique terminations stout, commonly elongated, Radiatind, columnra, fibrous, in interlocking aggregates, massive
Cleavage {010}, {110}, perfect
Fracture uneven
Hardness 3 - 4
Density 2.23 - 2.41
Name for Francois Pierre Nicolas Gillet de Laumont (1747-1834), who first found the mineral
Laumontite together with stilbite  from the Hvalfjördur area, Iceland.
Image width: 15 mm		 Laumontite from the Hvalfjördur area, Iceland.
Image width: 2 mm

up

Levyne
Formula: (Ca0.5,Na)6[Al6Si12O36] ·18 H2O
Symmetry: hexagonal
Habitus: crystals are thin tabular, with faces typically striated and rounded, in sheaflike or confused aggregates
Cleavage {1011}, indistinct
Fracture subconchoidal to uneven
Hardness 4 - 4.5
Density 2.09 - 2.16
Name after Armand Lévy (1794-1841), French mineralogist and crystallographer

Levyne from the Hvalfjördur area, Iceland.
Image width: 25 mm

up

Mesolite
Formula: Na16Ca16[Al48Si72O240] ·64 H2O
Symmetry: orthorhombic
Habitus: as prismatic crystals, elongated || {001}, commonly in hairlike tufts and aggregates of fibres, divergent, radiating, compact masses, in fibrous stalactites, porcelaneous. massive
Cleavage {110}, perfect
Fracture uneven
Hardness 5
Density 2.26
Name from the Greek for midle, alluding to its composition intermediate between natrolite and scolecite




Mesolite from the Hvalfjördur area, Iceland.
Image width: 30 mm		 Mesolite from the Hvalfjördur area, Iceland.
Image width: 20 mm

up

Phillipsite
Formula: K2(Na,Ca0,5)3[Al5Si11O32] ·12 H2O
Symmetry: monoclinic
Habitus: crystals always twinned, pseudosymmetrical;
striated || {001} on {010} ; equant to prismatic, or in spherical radiating aggregates,
twinning: cruciform single and double penetration twins on {001}, {021}, {110}, ubiquitous
Cleavage {010}, {100} , sistinct
Fracture uneven
Hardness 4 - 4.5
Density 2.20
Name for William Phillips (1775-1828). noted British mineralogist

Phillipsite from Limberg, Sasbach, Kaiserstuhl, Germany.
Image width: 5 mm

up

Scolecite
Formula: Ca8[Al16Si24O80] ·24 H2O
Symmetry: monoclinic, pseudotetragonal
Habitus: crystals are slender prsimatic, may be square in cross section, elongated and striated || {001}; characteristically in radiating sprays, fibrous masses, nodular, massive
Cleavage {110}, perfect
Fracture uneven
Hardness 5 - 5.5
Density 2.25 - 2.29
Name from the Greek for worm. alluding to its curling action when heated




Scolecite on adularia from Arvigo, Val Calanca; Switzerland.
Image width: 8 mm		 Scolecite together with adularia, quartz and epidot from Arvigo, Val Calanca; Switzerland.
Image width: 40 mm

up

Stellerite
Formula: Ca8[Al16Si56O144] ·56 H2O
Symmetry: orthorhombic
Habitus: single crystals show the forms {100}, {010}, {001} and {111}; commonly in spheres of radiating crystals
Cleavage {010}, perfect
Fracture
Hardness
Density 2.13
Name for Georg Wilhelm Steller (1709-1746), discoverer of the Komandorskiye (Commander) Islands, Russia




Stellerite from Hvammsvik/Hvalfjördur area, Iceland.
Image width: 20 mm		 Stellerite from Gibelsbach/Fiesch, Switzerland, with green Fluorite
Image width: 50 mm

up

Stilbite
Formula: NaCa4[Al9Si27O72] ·30 H2O
Symmetry: monoclinic
Habitus: crystals typically thin tabular, flattened on [010], in fasicled, sheaflike, or globular aggregates
Cleavage {010}, perfect
Fracture uneven
Hardness 3.5 - 4
Density 2.19
Name from the Greek for luster, in reference to its pearly luster






Stilbite together with laumontite from the Hvalfjördur area, Iceland.
Image width: 15 mm		 Stilbite from the Hvalfjördur area, Iceland.
Image width: 20 mm

up

Thomsonite
Formula: Ca7Na5[Al19Si21O80] ·24 H2O
Symmetry: orthorhombic, pseudotetragonal
Habitus: crystals commonly prismatic, acicular, or bladed, flattend on {010}, elongated and striated || [001]; in radiated spherical or columnar aggregates, smooth, globular, botryoidal, compact, massive
Cleavage {010}, perfect; {100} good
Fracture uneven to subconchoidal
Hardness 5 - 5.5
Density 2.23 - 2.39
Name for Dr. Thomas Thomson (1773-1852), Scottish chemist and mineralogist of Glasgow Scotland, who first analyzed the mineral




Thomsonite together with chabazite from the Hvalfjördur area, Iceland.
Image width: 35 mm		 Thomsonite together with chabazite from the Hvalfjördur area, Iceland.
Image width: 20 mm

up

Yugawaralite
Formula: Ca2[Al4Si12O32] ·8 H2O
Symmetry: monoclinic
Habitus: crystal flat tabular || {010}; in groups of nearly parallel crystals
Cleavage {401}, {100, distinct} {101} imperfect
Fracture conchoidal
Hardness 4.5 - 5
Density 2.20 - 2.23
Name for the locality where first found, Yugawara Hot Springs Japan



Yugawaralite from the Hvalfjördur area, Iceland.
Image width: 7 mm

up