5. Zeolite grade Si/Al molar
ratio
Some of the common mineral names
Low silica ≤2 Analcime , cancrinite , natrolite, phillipsite,
sodalite
Intermediate silica 2-5 Chabazite, faujasite, mordenite
High silica >5 ZSM-5, zeolite-β
6.
7.
8.
9. Classification of zeolites based on structure
group structure type examples
analcime interconnected 4 membered rings analcime, wairakite, leucite
natrolite chains of tetrahedra with 6.6Aº repeat distance natrolite, scolecite,thompsonite
chabazite parallel 6 or double 6 membered rings chabazite, glemenite, erionite
phillipsite parallel 4 membered rings phillipsite, gismodine, garronite
heulandite characteristic configuration with 4 or 5 membered
rings
heulandite
mordenite each tetrahedra of the framework belongs to
atleast one 5 membered ring
mordenite,dachiardite
faujasite framework based on cubic symmetry sodalite,faujasite, phillipsite
10. Type Biaxial (+)
RI values:
nα=1.491-1.505nβ=1.493-
1.503nγ=1.500-1.512
Max
Birefringence
δ = 0.009
Relief Moderate
C (Ca,Na2)[Al2Si7O18].7H2O
CS monoclinic
L
vitreous, but fibrous habits show
silky lustre
F&H
tabular, rarely granular crystals;
also nodular or massive
TR transparent- subtransparent
COL white, brick red, brown
HD 3.5-4.0
SG 2.2
CL {010} perfect
F subconchoidal
11.
12. C CaAl2Si3O10·3H2O
CS monoclinic (pseudo trigonal)
L
vitreous, but fibrous habits
show silky lustre
F&H
radiating clusters of fibrous
or prismatic crystals;
crystals; also nodular or
massive
TR transparent
COL white
HD 5
SG 2.25-2.29
CL perfect {110}
Type Biaxial (-)
RI values:
nα=1.507-
1.513nβ=1.516-
1.520nγ=1.517-1.521
Max
Birefringence
δ = 0.010
Relief low
13.
14. C (Ca, Na2,K2)[Al2Si7O18].7H2O
CS monoclinic
L vitreous
F&H platy, sheaf like radiating
TR transparent- subtransparent
COL white
HD 3.5-4.0
SG 2.1-2.2
CL {010} perfect, {010} poor
F subconchoidal
Type Biaxial (-)
RI values:
nα=1.479-1.492nβ=1.485-
1.53nγ=1.489-1.505
Max
Birefringence
δ = 0.0100-0.0130
Relief low
15.
16. C (Ca[Al2Si4O12].6H2O
CS trigonal
L vitreous
F&H rhombohedral
TR transparent- translucent
COL white
HD 4.5
SG 2.1
CL
{good {1011}rhombohedral
cleavages present
F subconchoidal
Type Biaxial (+/-)
RI values:
nα=1.478 - 1.487
nβ=1.480 - 1.490
nγ=1.480 - 1.493
Max
Birefringence
δ = 0.002 - 0.006
Relief moderate
17.
18. C (Na2Al2Si3O10 · 2H2O
CS Orthorhombic
L Vitreous, Pearly
F&H platy, sheaf like radiating
TR Transparent, Translucent
COL
White, Colorless, Red, Yellow,
Brown, Green, bluish
HD 5 - 5.5
SG 2.2 - 2.26
CL {010} perfect, {010} poor
F Irregular/Uneven
Type Biaxial (+)
RI values:
nα=1.473 - 1.483
nβ=1.476 - 1.486
nγ=1.485 - 1.496
Max
Birefringence
δ = 0.012 - 0.013
Relief Moderate
