HELP WITH ZEOLITE IDENTIFICATION

Hi all,

I recently visited a new zeolite locality at the Garron Plateau, County Antrim Northern Ireland and have found some specimens which i am unsure of.

The photos 1 and 1a show white elongated crystals approximately 3 mm long in association with clear analcime. Terminations are very irregular although the crystals seem to have a triangular cross section.

Photo 2 shows a white crystal approximately 4mm long on Thomsonite. I'm guessing it is Phillipsite but your opinions on both minerals are as always greatly appreciated.

Many thanks

Trevor

The second probably Calcite
For the first, if the section is triangular, is possible a trigonal specie.
Ciao
Ferdinando

Hi Trevor

Just my opinion for what it`s worth.

Think that photo2 resembles the zeolite " harmotome ".

Or is a member of the harmotone - phillipsite series.

Well worth looking into these options.

Hope this helps good luck.

Regards george

Laumontite for the first?

Hi Rob, laumontite is monoclinic. Impossible with triangular section ::o

Hi Ferdinando

Trevor ( Re photo 1 ) stated in post 1 that:-

Terminations are very irregular although the crystals seem to have a triangular cross section.

So open for discussion.

Just my point of view.

Regards george

The crystals in photograph one appear to be aggregates of elongated crystals, and so the cross section of the aggregates is not very diagnostic. They appear recrystallized, possibly pseudos or an overgrowth of one species on another. Photo 1a also does not appear to be primary, and is an aggregate. Photo 2 has the dessicated appearance I would expect in laumontite. Since photographs are two dimensional representations of three dimensional items, it would be helpful to see a side image of this one. I am thinking the crystal might not be as equant as it might appear, making laumontite more likely and some member of the phillipsite group less, but can't be sure. Certainly, all of these might have laumontite in their past, with the specimen in photograph 1 possibly being overgrown by a generation of very finely crystallized analcime or calcite.

Bob Meyer



Edited 1 time(s). Last edit at 10/31/2011 04:24AM by Robert Meyer.

Hi Trevor

For Photo 2 I'd say apophyllite on either thomsonite or prehnite. Photo 1, some sort of pseudomorph after laumontite.
Regards, Wolfgang

I take full responsibility for my words - you can't recognize all zeolites on photos and definitely not so small individuals. We can only guess - so do I: pictures nr 1 and 2: laumontite (why not scolecite??) on "something", 3 - phillipsite on "something". Regards :)

I would have to guess calcite for the second one. Possibly calcite for the first one as well. It's quick to test and rule in or out, and no harm done if they are something else.

Hi all,

Thanks so much for all of your contributions. Apologies also as I should have carried out the HCl test at the start!! However I have done it now and it would seem that specimen 1 is indeed a variety of calcite, although not one I have previously seen before.

Specimen 2 shows no reaction to the HCl. Unfortunately I cant really get an alternative view of the initial crystal however I have attached two other photos showing multiple full and partial crystals which hopefully may prove useful.

Many thanks again to all.

Trevor

Hello Trevor,

specimen 2 is clearly Apophyllite on a crust of Thomsonite. Typical paragenesis for the area.

Regards

Volker

"I should have carried out the HCl test at the start!! However I have done it now and it would seem that specimen 1 is indeed a variety of calcite, although not one I have previously seen before. "
- honestly I will be very surprised, Ca-rich zeolites can react with HCl.

"specimen 2 is clearly Apophyllite on a crust of Thomsonite."

I agree with Volker.


The prismatic white mineral (specimen 1) looks like calcite to me.

Thanks guys for all your comments and opinions ... all greatly appreciated!!!

Regards,

Trevor

The unidentified 2b is a one best photo and is Apophyllite according to Uwe and Volker.
for the first Calcite is a trigonal specie! X(

i have synthesised zeoites but i dont know how i can identify the type of zeolites i have made. any help with what is called the JCDS thing. it where do i get ?