Dear Konstantinos,

The world's largest database for mineralogy and the (also optical) properties of mineral species is "mindat.org". Here you will find the optical properties of analcime, mordenite, and heulandite, as well as numerous photos of mineral specimens.

The optical properties and color images in thin sections of the mineral species (or mineral groups) analcime, mordenite, clinoptilolite, and heulandite (and other zeolitic-type minerals) can be found in the (1.075 pages) book:

"Atlas de Asociaciones Minerales en Lámina Delgada"

by Joan-Carles Melgarejo (1997).

Edicions de la Universitat de Barcelona. ISBN: 84-89829-24-1

Kind regards,

Guenter Grundmann

Dear @Guenter Grundmann

Thank you for your assistance that was really helpful!!

Dear Mr. Papastergiou,

for a precise determination of zeolites in samples a thin section analysis will hardly be enough due to the substitution mechanism of the major and minor elements (e.g. Cs) and therefore a method providing you with the microchemical data such as EMPA or SEM-EDX/WDX and the crystallographic ones, e.g., XRD is highly recommended. For a routine analysis in support of mapping thin sections might be the first step to get some information.

H.G.Dill

p.s. DILL, H.G., FUESSL, M. and BOTZ, R. (2007) Mineralogy and (economic) geology of zeolite-carbonate mineralization in basic igneous rocks of the Troodos Complex, Cyprus.-

Neues Jahrbuch für Mineralogie Abhandlungen, 183: 251-268.

DILL, H.G., TECHMER, A., BOTZ, R., DOHRMANN, R. and KAUFHOLD, S. (2012) Hypogene and supergene alteration of the zeolite-bearing pyroclastic deposits at Tell Rimah, Jordan, and rift-related processes along the Dead-Sea-Transform Fault System during the Quaternary.- Journal of Volcanology and Geothermal Research, 239-240: 49-68.

DILL, H.G., DOHRMANN, R., KAUFHOLD, S. and TECHMER, A. (2014) Provenance analysis and thermo-dynamic studies of multi-type Holocene duricrusts (1700 BC) in the

Sua Salt Pan, NE Botswana.- Journal of African Earth Sciences, 96: 79-98.

Dear Harald G. Dill ,

Thank you for your assistance! The thin section analysis is indeed the first step to get some information for my thesis.

You can find excellent petrography videos of thin sections on this channel:

https://www.youtube.com/channel/UCVeEaFSYjWfoY35idMlqNCA/playlists

There is even a playlist about zeolites.

The only issue is that it is in Portuguese, but I believe you can turn the captions on.