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Identity HelpAragonite PS Hex Trillings from Morocco

10th Mar 2015 11:58 GMTJay I. G. Roland

03071950015659013945848.jpg
Hello all. A recent purchase has me a tad puzzled by the description on the label. It actually says...


Aragonite ps. Hex. Trillings

Tagenenait

Morocco


I gather that the 'Tagenenait' should read 'Tazenakht' but the 'pseudomorph hex trillings' has me stumped. Has it 'morphed' into Aragonite or has the Aragonite 'morphed' into something else?


Two pictures below are front and back and both are circa 15mm (actual specimen size).


Any guidance gratefully recieved.


Regards,


Jay.

03334550015667083455768.jpg

10th Mar 2015 12:58 GMTOwen Melfyn Lewis

03807180015659014085697.jpg
Hi Jay,


Not a trilling IMHO but a known and fairly common form of crystalisation for aragonite.


For comparison, here's a trilling (sometimes called a sixling) in chrysoberyl, a mineral that fairly often shows this crystal form:

.

10th Mar 2015 13:26 GMTVik Vanrusselt Expert

Hello Jay,


"PS Hex" probably means "pseudohexagonal" in this case.


As in: three (hence the "trilling") orthorhombic Aragonite crystals combine to form one "hexagonal-looking" crystal.


Multiply that same "combining action" a few times and you get "hexagonal looking" Aragonite crystal aggregates.


Vik

10th Mar 2015 15:22 GMTRoger Lang Manager

Agree with Vik,

these are pseudohexagonal twinned (threelings - trillings) aragonite xls, but most probably from Tazouta, not Tazenakht.

Compare here: http://www.mindat.org/loc-2399.html


Cheers

Roger

10th Mar 2015 15:44 GMTOwen Melfyn Lewis

Thanks Vik. My understanding was that the term trilling is applied only to cyclic interpenetrant tinning. It's good to learn that it is applied to cyclic contact twinning forming sometimes distorted pseudo-forms also.

11th Mar 2015 12:35 GMTJay I. G. Roland

Owen, Vik & Roger, many thanks for your thoughts and explanations......things are much clearer now!


My initial mistake of course was to assume the 'ps' meant pseudomorph. I did look up 'trillings' in the good old OED2 and got an idea of its meaning and have since read up on pseudoheaxagonal crystal forms. So much to learn and so little time.......


Thanks also Roger for the correction of the location, my label has now been updated.


Quite a beauty for a quid methinks!


Thanks again,


Regards,


Jay.


PS: Owen, that's a corker of a Chrysoberyl.....I feel quite green :-)
 
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