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Note on the distinguishing differences between clinoptilolite and heulandite (h

"Zeolite mineral species shall not be distinguished solely on the basis of the framework Si : Al ratio. An exception is made in the case of heulandite and clinoptilolite; heulandite is defined as the zeolite mineral series having the distinctive framework topology of heulandite and the ratio Si : Al < 4.0. Clinoptilolite is defined as the series with the same framework topology and Si : Al ≥ 4.0.

Application of the rule
Many zeolites have a widely variable Si : Al ratio, but this, in itself, is not regarded as providing adequate grounds for recognition of separate species. The exception is based on entrenched usage of the names heulandite and clinoptilolite, and their convenience for recognizing an important chemical feature. The cutoff value adopted (following Boles 1972) is arbitrary in a continuous range of compositions. The usual 50% compositional rule cannot be applied, as there are no clearly defined Si,Al end-member compositions for heulandite and clinoptilolite. Thermal stability has been used by some investigators to distinguish clinoptilolite from heulandite. This is a derivative property, however, suggested by Mumpton (1960) as an aid to identification, and it is not appropriate as the basis for definition. Alietti (1972) and Boles (1972) have shown that there is no gap in composition either in framework or extra-framework cation contents between heulandite and clinoptilolite, and that samples transitional in composition show intermediate properties in terms of thermal stability.

The cation content is highly variable. Ca-, Na-, and K-dominant compositions are known, and Sr, Ba, and Mg are in some cases substantial. TSi in the range 0.80–0.84. Minerals with the same framework topology but with TSi < 0.80, Si/Al < 4.0 are classified as heulandite, with which clinoptilolite forms a continuous series. Monoclinic, C2/m, or C2, or Cm.

The cation content is highly variable. Ca-, Na-, K-, and Sr-dominant compositions are known, and Ba and Mg are in some cases substantial. TSi in the range 0.71 to 0.80."

Classification of Clinoptilolite

1 : Zeolite group - True zeolites

16 : Silicates Containing Aluminum and other Metals
10 : Aluminosilicates of Ca and alkalis

Physical Properties of Clinoptilolite

Hardness (Mohs):
3½ - 4

Optical Data of Clinoptilolite

Biaxial (+/-)
RI values:
nα = 1.476 - 1.491 nβ = 1.479 - 1.493 nγ = 1.479 - 1.497
Measured: 31° to 48°
Max Birefringence:
δ = 0.003 - 0.006
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
r > v to r < v strong

Relationship of Clinoptilolite to other Species

16.10.4Thomsonite-CaNaCa2(Al5Si5)O20 · 6H2O
16.10.5Gonnardite(Na,Ca)2(Si,Al)5O10 · 3H2O
16.10.6MesoliteNa2Ca2(Si9Al6)O30 · 8H2O
16.10.8Garronite-CaNaCa2.5(Si10Al6)O32 · 14H2O
16.10.9BoggsiteNa3Ca8(Si77Al19)O192 · 70H2O
16.10.10Herschelite(Na2,K2,Ca,Sr,Mg)2[Al2Si4O12]2 · 12H2O
16.10.12Fedorite(K,Na)2.5(Ca,Na)7Si16O38(OH,F)2 · 3.5H2O
16.10.13WillhendersoniteKCa(Si3Al3)O12 · 5H2O
16.10.14BarreriteNa2(Al2Si7)O18 · 6H2O
16.10.15Mordenite(Na2,Ca,K2)4(Al8Si40)O96 · 28H2O
16.10.16ReyeriteNa2Ca14Al2Si22O58(OH)8 · 6H2O
16.10.20GobbinsiteNa5(Si11Al5)O32 · 11H2O
16.10.23OffretiteKCaMg(Si13Al5)O36 · 15H2O
16.10.24PerlialiteK9NaCa(Si24Al12)O72 · 15H2O
16.10.27Sodium Dachiardite(Na2,Ca,K2)4-5Al8Si40O96 · 26H2O
16.10.28Mazzite-MgMg5(Si26Al10)O72 · 30H2O
16.10.29RoggianiteCa2BeAl2Si4O13(OH)2 · nH2O (n < 2.5)

Other Names for Clinoptilolite

Name in Other Languages:

Other Information

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Clinoptilolite

Reference List:
Hey, M.H. & F.A. Bannister (1934): Clinoptilolite. Min. Mag. 23, 556-559.

Mumpton, F.A. (1960): Clinoptilolite redefined: Am. Min. 45, 351-369.

Alietti, A. (1972): Polymorphism and crystal chemistry of heulandite and Clinoptilolite. Am. Min. 57, 1448-1462.

Koyama, K. & Y. Takeuchi (1977): Clinoptilolite: The distribution of potassium atoms and its role in thermal stability. Zeits. Kristallogr. 145, 216-239.

Armbruster, T. (1993): Dehydration mechanism of clinoptilolite and heulandite: Single-crystal X-ray study of Na-poor, Ca-, K-, Mg-rich clinoptilolite at 100K. American Mineralogist 78, 260-264.

Gabuda, S.P., Kozlova, S.G., Kolesnikov, A.S., Petrov, A.K. (2013): Microwave Absorption and Structure of Zeolite Water in Heulandite and Clinoptilolite by 1H NMR. Journal of Structural Chemistry, 54, S119-S125.

Internet Links for Clinoptilolite URL:
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Localities for Clinoptilolite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
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