[Rockhounds] 18 sided Beryl crystal

[Peter Richards]

Sorry to say that the pictures are not detailed enough to show anything distinctive about the morphology.  But these do look like an undistorted crystal.  If they have 18 prism faces, as you say, they probably have a combination of a hexagonal prism and a di-hexagonal prism.  That’s pretty exciting - I’ve never actually seen a beryl crystal like that.  However, it is a single crystal of unusual morphology, not a twinned crystal.

I hope you find the specimen!

Pete
___________________________
R. Peter Richards, Ph.D.
rpr at heidelberg.edu
Morphological Crystallographer

> On Mar 5, 2019, at 5:03 PM, Kreigh Tomaszewski <kreigh at gmail.com> wrote:
> 
> I could not find the specimen, but I found a couple pictures (sent to Peter
> off list). Mine was actually an 18 sided crystal (not 12 as I remembered).
> 
> On Tue, Mar 5, 2019 at 4:46 PM Peter Richards <rpr at heidelberg.edu> wrote:
> 
>> I may rapidly become viewed as a crystallographic curmudgeon, but I will
>> report that twinning is not known in beryl.  Kreigh, can you provide more
>> description and maybe a picture somewhere?
>> 
>> Pete Richards
>> ___________________________
>> R. Peter Richards, Ph.D.
>> rpr at heidelberg.edu
>> Morphological Crystallographer
>> 
>>> On Mar 5, 2019, at 3:31 PM, Kreigh Tomaszewski <kreigh at gmail.com> wrote:
>>> 
>>> I have a small 12 sided crystal from the same locality that is a twinned
>>> crystal, and the faces are pretty close to being even. Your's looks more
>>> like a group of crystals that grew together, but not quite in the same
>> axis
>>> alignment.
>>> 
>>> On Tue, Mar 5, 2019 at 2:47 PM <larryrush at att.net> wrote:
>>> 
>>>> I acquired this piece many years ago, in a trade. It may be described
>> as a
>>>> hexagonal tripyramid (?). Although it does have 18 prism faces, few are
>> of
>>>> the same width, and the symmetry is not obvious or easily defined.  The
>>>> locality is the Mc Ginnes Mine, Wentworth, Grafton Co., NH, noted for
>> these
>>>> unusual beryls. It is 2X3X13 cm in size, and has no terminations.
>>>> 
>>>> 
>>>> 
>>>> I got it due to its unusual habit, and would appreciate any comments
>> that
>>>> help to define it, crystallographically.
>>>> 
>>>> 
>>>> 
>>>> <https://www.irista.com/gallery/sdsy1wlie6l5>
>>>> https://www.irista.com/gallery/sdsy1wlie6l5
>>>> 
>>>> Larry
>>>> 
>>>> 
>>>> 
>>>> Larry Rush
>>>> 
>>>> BS Geology
>>>> 
>>>> ConnRox Minerals
>>>> 
>>>> Guilford, CT
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>> ---
>>>> This email has been checked for viruses by Avast antivirus software.
>>>> https://www.avast.com/antivirus
>>>> _______________________________________________
>>>> Rockhounds mailing list
>>>> Subscription Services:
>>>> 
>> http://rockhounds.drizzle.com/mailman/listinfo/rockhounds_rockhounds.drizzle.com
>>>> List Usage Policy:
>>>> http://Tomaszewski.net/Kreigh/Rockhounds/Rockhounds.shtml
>>>> 
>>> _______________________________________________
>>> Rockhounds mailing list
>>> Subscription Services:
>> http://rockhounds.drizzle.com/mailman/listinfo/rockhounds_rockhounds.drizzle.com
>>> List Usage Policy:
>> http://Tomaszewski.net/Kreigh/Rockhounds/Rockhounds.shtml
>> 
>> _______________________________________________
>> Rockhounds mailing list
>> Subscription Services:
>> http://rockhounds.drizzle.com/mailman/listinfo/rockhounds_rockhounds.drizzle.com
>> List Usage Policy:
>> http://Tomaszewski.net/Kreigh/Rockhounds/Rockhounds.shtml
>> 
> _______________________________________________
> Rockhounds mailing list
> Subscription Services:  http://rockhounds.drizzle.com/mailman/listinfo/rockhounds_rockhounds.drizzle.com
> List Usage Policy: http://Tomaszewski.net/Kreigh/Rockhounds/Rockhounds.shtml