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
31 Oct-12:39:30 Re: collection of michael shaw (Michael Shaw)
31 Oct-05:34:05 Re: munich show (mineralientage) 2024 (James Catmur)
30 Oct-14:07:27 Re: introduction with some pictures (Philippe Durand)
30 Oct-11:47:09 Re: contribution dr. Menor-salván - bertrandite from portuguese pegmatites - (51) (Fmf Forum)
30 Oct-11:46:20 Contribution dr. Menor-salván - bertrandite from portuguese pegmatites - (51) (Fmf Forum)
30 Oct-09:41:36 Re: munich show (mineralientage) 2024 (James Catmur)
30 Oct-09:36:03 Re: introduction with some pictures (James Catmur)
30 Oct-08:50:48 Re: introduction with some pictures (Michael Shaw)
30 Oct-05:58:51 Introduction with some pictures (Pegmatiteappreciator)
29 Oct-23:45:34 My 44th visit to the mineralientage in munich since 1977 (Roger Warin)
29 Oct-09:20:39 Collection of carles millan: fluorite from erongo (Carles Millan)
29 Oct-03:57:49 Re: is this a gold ore??? (Vdhinesh79)
29 Oct-00:04:37 Re: collection of volkmar stingl (Volkmar Stingl)
28 Oct-12:12:31 Re: is this a gold ore??? (Vdhinesh79)
28 Oct-12:10:40 Re: is this a gold ore??? (Jordi Fabre)
28 Oct-12:07:43 Re: is this a gold ore??? (Matt_zukowski)
28 Oct-11:55:16 Re: is this a gold ore??? (Lluis)
28 Oct-10:22:03 Re: is this a gold ore??? (Vdhinesh79)
28 Oct-06:27:20 Re: is this a gold ore??? (James Catmur)
28 Oct-06:01:21 Re: is this a gold ore??? (Vdhinesh79)
28 Oct-04:28:43 Re: the mim museum in beirut, lebanon (Mim Museum)
28 Oct-03:29:52 Re: is this a gold ore??? (Vdhinesh79)
28 Oct-02:35:31 Re: is this a gold ore??? (Alfredo)
27 Oct-17:09:16 What might this be? (Todd Willis)
27 Oct-16:38:02 Re: sphalerite from kulmberg austria (Jordi Fabre)

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
115978


The time now is Oct 31, 2024 18:38

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.
Unusual Fluorite
  
  Index -> Minerals and Mineralogy
Like


View previous topic :: View next topic  
Author Message

Jesse Fisher




Joined: 18 Mar 2009
Posts: 631
Location: San Francisco


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jun 29, 2010 00:57    Post subject: Unusual Fluorite  

Fluorite crystals, though usually roughly equidimensonal, are sometimes found in mines around the Weardale area in Northern England showing a pronounced tabular appearance due to unequal growth on the three crystallographic axes. This one, found in mid-June 2010 at the Rogerley mine appears to have abandoned a few right angles as well.


odd-2010-5977r.jpg
 Description:
an oddly shaped fluorite from the Rogerley Mine, 7 cm tall.
 Viewed:  22069 Time(s)

odd-2010-5977r.jpg



odd-2010-5979r.jpg
 Description:
a second view
 Viewed:  22065 Time(s)

odd-2010-5979r.jpg


Back to top
Reply to topic Reply with quote
Like
   

gemlover




Joined: 31 Dec 2008
Posts: 211
Location: Easley, SC


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jun 29, 2010 02:27    Post subject: Re: Unusual Fluorite  

What a beautiful sample, thank you for sharing with us.

John

_________________
John
John Atwell Rasmussen, Ph.D.. AJP
Geologist and Gemologist
Back to top
Reply to topic Reply with quote
Like
   

James Catmur
Site Admin



Joined: 14 Sep 2006
Posts: 1392
Location: Cambridge


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jun 29, 2010 06:19    Post subject: Re: Unusual Fluorite  

Nice one!

James
Back to top
Reply to topic Reply with quote
Like
   

Peter Megaw
Site Admin



Joined: 13 Jan 2007
Posts: 965
Location: Tucson, Arizona


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jun 29, 2010 08:50    Post subject: Re: Unusual Fluorite  

Keep digging Jesse!

Say Hi at the pub for me

_________________
Siempre Adelante!
Back to top
Reply to topic Reply with quote
Like
   

chris
Site Admin



Joined: 12 Jul 2007
Posts: 538
Location: Grenoble


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jun 29, 2010 10:10    Post subject: Re: Unusual Fluorite  

Hi Jesse,

Let's hope you'll find others like this !

Christophe
Back to top
Reply to topic Reply with quote
Like
   

Jesse Fisher




Joined: 18 Mar 2009
Posts: 631
Location: San Francisco


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jun 29, 2010 10:17    Post subject: Re: Unusual Fluorite  

I haven't seen one quite like this in 12 years of digging there. Sadly, a bit dinged up but definitely going into the oddities collection.
Back to top
Reply to topic Reply with quote
Like
   

Colleen Thomson




Joined: 27 Mar 2009
Posts: 17
Location: 50 miles North of London


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jun 29, 2010 17:04    Post subject: Re: Unusual Fluorite  

Cool! i love these oddities. They make you sit up in your seat a bit more and ask questions - like, how did that particular crystal grow like that and not the ones surrounding it from the same pocket? was its growth altered by space restrictions?

I'm no crystallographer - i tend to glaze over after a while :-) but i'm still fascinated by it.
Nice find, Jesse!

_________________
Cheers,
Colleen :-)
Back to top
Reply to topic Reply with quote
Like
   

Jesse Fisher




Joined: 18 Mar 2009
Posts: 631
Location: San Francisco


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jun 29, 2010 22:38    Post subject: Re: Unusual Fluorite  

Not being a crystallographer myself (just a dig in the dirt style geologist) I'm at a loss to explain such things. The North Pennines ore deposits are low temperature MVT, quite similar to the well known ones in Southern Illinois, hence the fluorite is always cubic habit, without octahedral or dodecahedral forms. North Pennines fluorite does show some very unusual characteristics, including the omni-present twinning, well developed vicinal (or growth) faces, and the occasional distortions to the cube. The photo attached is of one of the most extreme examples I have seen, a crystal from the Boltsburn mine now in the NHM London (Russell collection). I am clueless as to what causes these to be so common in the fluorite from the district, and seemingly rare elsewhere, and have never encountered any speculation about it. Anyone care to engage in some speculative arm waving?


Boltsburn-NHM1918r.jpg
 Description:
 Viewed:  21824 Time(s)

Boltsburn-NHM1918r.jpg


Back to top
Reply to topic Reply with quote
Like
   

John S. White
Site Admin



Joined: 04 Sep 2006
Posts: 1297
Location: Stewartstown, Pennsylvania, USA


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jun 30, 2010 04:29    Post subject: Re: Unusual Fluorite  

Jesse:

Can't offer any thoughts with respect to how these form and the one you illustrate is by far the most bizarre that I have ever seen. For the benefit of FMF viewers who are not geologists, can I persuade you to define MVT?

Here are a couple that are more typical from the Black Dene mine, Weardale, Durham. The one on the left is 5 cm in length.



fluorite - England SC-273 (on left).JPG
 Description:
 Viewed:  21760 Time(s)

fluorite - England SC-273 (on left).JPG



_________________
John S. White
aka Rondinaire
Back to top
Reply to topic Reply with quote
Like
   

Jordi Fabre
Overall coordinator of the Forum



Joined: 07 Aug 2006
Posts: 4929
Location: Barcelona


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jun 30, 2010 04:48    Post subject: Re: Unusual Fluorite  

My contribution to Fluorite's oddities from UK.

In a first view, as a Quartz, it looks rare. And it is rare, because it has the form of octahedral Fluorite, previously existing and substituted by the Quartz. More curious is to observe that the surface is cryptocrystalline Quartz (Chalcedony) but the core of the octahedron, where Fluorite primarily was, is hollow and consists of little geodes covered by Quartz crystals.



Quartz after Fluorite Wheal Mary Ann UK.jpg
 Description:
Quartz after Octahedral Fluorite
Wheal Mary Ann, Menheniot, Liskeard, Cornwall, England, United Kingdom
Specimen size: 7.5 × 6.4 × 3.3 cm.
Main crystal size: 1.5 × 1.5 cm.
Former Jan Buma collection. Number 940105
Photo from "Reference Specimens"
 Viewed:  21776 Time(s)

Quartz after Fluorite Wheal Mary Ann UK.jpg


Back to top
Reply to topic Reply with quote
Like
   

GneissWare




Joined: 07 Mar 2008
Posts: 1287
Location: California


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jun 30, 2010 09:30    Post subject: Re: Unusual Fluorite  

John S. White wrote:
For the benefit of FMF viewers who are not geologists, can I persuade you to define MVT?


Mississippi Valley-type (MVT) lead-zinc deposits are a varied family of epigenetic ore deposits that form predominantly in dolostone and in which lead and zinc are the major commodities.

There are lots of online references available. This one from USGS is particularly good:
https://pubs.usgs.gov/of/1995/ofr-95-0831/CHAP30.pdf
(link normalized by FMF)
Back to top
Reply to topic Reply with quote
Like
   

Jesse Fisher




Joined: 18 Mar 2009
Posts: 631
Location: San Francisco


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jun 30, 2010 09:48    Post subject: Re: Unusual Fluorite  

To add a bit of detail - they form at very low temperature (less than 200 C) and typically have a fairly simple mineralogy. The Viburnum Trend and Tri-State district deposits of the central US are primarily galena and sphalerite with lesser pyrite, chalcopyrite, calcite, dolomite, etc. Fluorite-containing varieties are found in Southern Illinois and adjoining areas of Kentucky, and the North Pennine Mountains in England. All are hosted by carbonate rocks, either limestone or dolostone.
Back to top
Reply to topic Reply with quote
Like
   

Colleen Thomson




Joined: 27 Mar 2009
Posts: 17
Location: 50 miles North of London


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 07, 2010 12:58    Post subject: Re: Unusual Fluorite  

thanks for the explanations, 'arm waving' and pictures, guys. The NHM crystal is astonishing!
Jordi - the Wh Mary Ann Ps.Chalcedony after Octo Fluorite are pretty cool - Ive got a few of them :-)

_________________
Cheers,
Colleen :-)
Back to top
Reply to topic Reply with quote
Like
   

kywawa




Joined: 17 Jul 2010
Posts: 6
Location: new york

View user's profile

Send private message

PostPosted: Jul 30, 2010 04:12    Post subject: Re: Unusual Fluorite  

That's great..i always can look such beautiful minerals when i login it this forum..so cool..thanks for sharing.
_________________
Everything in the world is wonderful. Left your hearts, your soul, your power
Back to top
Reply to topic Reply with quote
Like
   

James Catmur
Site Admin



Joined: 14 Sep 2006
Posts: 1392
Location: Cambridge


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Sep 06, 2010 14:16    Post subject: Re: Unusual Fluorite  

This is another long one from the British Musuem of Natural History, in London.


DSCF1383.JPG
 Description:
Fluorite, twinned, elongated crystals, Boltsburn Mine, County Durham, about 20cm long
 Viewed:  20754 Time(s)

DSCF1383.JPG


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