We use cookies to show content based on your preferences. If you continue to browse you accept their use and installation. More information. >

FMF - Friends of Minerals Forum, discussion and message board
The place to share your mineralogical experiences


Spanish message board






Newest topics and users posts
28 Mar-09:37:50 Re: 2 unknowns co-occurring with caledonite, grand reef mine, az (Cfrench58)
27 Mar-19:47:08 Re: 2 unknowns co-occurring with caledonite, grand reef mine, az (Pete Richards)
27 Mar-16:15:44 Re: 2 unknowns co-occurring with caledonite, grand reef mine, az (Cfrench58)
27 Mar-15:18:59 Re: 2 unknowns co-occurring with caledonite, grand reef mine, az (Alfredo)
27 Mar-14:39:29 2 unknowns co-occurring with caledonite, grand reef mine, az (Cfrench58)
27 Mar-05:21:48 Re: the mim museum in beirut, lebanon (Mim Museum)
27 Mar-05:03:26 Re: trying to find information on rose/pink quartz and tourmaline associations. (Ning)
27 Mar-02:39:50 Re: the mim museum in beirut, lebanon (Tobi)
27 Mar-00:23:28 Re: collection of volkmar stingl (Volkmar Stingl)
26 Mar-00:53:41 Re: collection of volkmar stingl (Volkmar Stingl)
25 Mar-13:32:10 Re: collection of michael shaw (Michael Shaw)
25 Mar-00:25:58 The mizunaka collection - quartz (Am Mizunaka)
23 Mar-13:35:22 Re: collection of firmo espinar (Firmo Espinar)
22 Mar-08:32:28 Re: collection of michael shaw (Michael Shaw)
22 Mar-04:20:41 Re: the mim museum in beirut, lebanon (Mim Museum)
21 Mar-22:49:19 Re: green seam. Looks like it in a state of decay. (Ning)
21 Mar-22:47:40 Re: green seam. Looks like it in a state of decay. (Ning)
21 Mar-22:45:25 Re: green seam. Looks like it in a state of decay. (Ning)
21 Mar-15:34:23 Re: the mizunaka collection - quartz (Am Mizunaka)
21 Mar-14:35:08 Re: jim’s mineral collection (Jim Wilkinson)
21 Mar-14:15:36 The 4th phoenix heritage mineral show (phms) hosted by mineralogical society of arizona (m (Chris Whitney-smith)
21 Mar-04:36:10 Re: the mizunaka collection (Tobi)
21 Mar-04:11:47 Re: jim’s mineral collection (James Catmur)
20 Mar-23:34:15 The mizunaka collection - quartz (Am Mizunaka)
20 Mar-18:13:16 Re: jim’s mineral collection (Jim Wilkinson)

For lists of newest topics and postings click here


RSS RSS

View unanswered posts

Why and how to register

Index Index
 FAQFAQ RegisterRegister  Log inLog in
 {Forgotten your password?}Forgotten your password?  

Like
111802


The time now is Mar 28, 2024 12:12

Search for a textSearch for a text   

A general guide for using the Forum with some rules and tips
The information provided within this Forum about localities is only given to allow reference to them. Any visit to any of the localities requires you to obtain full permission and relevant information prior to your visit. FMF is strictly against any illicit activities related to collecting minerals.
Termination in a tourmaline crystal
  
  Index -> Minerals and Mineralogy
Like
13


View previous topic :: View next topic  
Author Message

marco campos-venuti




Joined: 09 Apr 2014
Posts: 206
Location: Sevilla


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Aug 28, 2018 08:37    Post subject: Termination in a tourmaline crystal  

I had this green tourmaline crystal on a recent trip to Brazil. It comes from Barra de Salinas pegmatite. It seems to me a quite unusual termination. Most of crystals from pegmatites have a lower symmetry, but this crystal has a very high symmetry.
Any comment? Can it be a clue for a different composition?



IMG_1370.JPG
 Mineral: tourmaline
 Locality:
Barra de Salinas, Coronel Murta, Jequitinhonha, Minas Gerais, Brazil
 Description:
 Viewed:  6262 Time(s)

IMG_1370.JPG



IMG_1373.JPG
 Locality:
Barra de Salinas, Coronel Murta, Jequitinhonha, Minas Gerais, Brazil
 Description:
 Viewed:  6251 Time(s)

IMG_1373.JPG


Back to top
Reply to topic Reply with quote
Like
9
   

Pete Richards
Site Admin



Joined: 29 Dec 2008
Posts: 828
Location: Northeast Ohio


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Aug 28, 2018 08:55    Post subject: Re: Termination in a tourmaline crystal  

A very nice crystal indeed, Marco! I have a small one from that pegmatite with a beautiful blue-green color, but it is not nearly as perfectly developed as yours.

I have had the opportunity to examine suites of dozens of tourmaline crystals from individual pockets from the Havey Quarry and Mount Mica in Maine. It seems likely that the chemistry in a particular pocket would be consistent throughout the pocket. But in all cases, some of the crystals are ideally developed while others are quite unbalanced in terms of symmetry - even missing some faces that should be there.

I don't know what accounts for this variablilty, but this observation suggests it is not chemistry!

It is also true that crystals from certain pockets are distinctly different in habit and color from those in pockets nearby. In this case, I suspect chemical differences may have played a role.

_________________
Collecting and studying crystals with interesting habits, twinning, and epitaxy
Back to top
Reply to topic Reply with quote
Like
3
   

John S. White
Site Admin



Joined: 04 Sep 2006
Posts: 1295
Location: Stewartstown, Pennsylvania, USA


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Aug 28, 2018 13:13    Post subject: Re: Termination in a tourmaline crystal  

The Mercedes-like trio of narrow faces on the termination are quite odd. I have a large number of tourmaline crystals in my crystal collection but I do not have one like that. It resembles what you see in slices of liddicoatite. Very nice and green too.
_________________
John S. White
aka Rondinaire
Back to top
Reply to topic Reply with quote
Like
   
Display posts from previous:   
   Index -> Minerals and Mineralogy   All times are GMT - 5 Hours
Page 1 of 1
    

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


All pictures, text, design © Forum FMF 2006-2024


Powered by FMF