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11 May-21:01:46 Re: the mizunaka collection - fluorite (Am Mizunaka)
11 May-08:49:40 Re: a mineralogical trip through germany / baden-wuerttemberg (Tobi)
11 May-08:44:49 Re: the mizunaka collection - fluorite (Tobi)
11 May-06:20:29 Re: collection of volkmar stingl (Volkmar Stingl)
11 May-04:39:24 Re: soon 15 years of fmf and how to achieve many more (James Catmur)
11 May-02:11:53 Re: soon 15 years of fmf and how to achieve many more (Peter Lemkin)
10 May-23:55:01 The mizunaka collection - fluorite (Am Mizunaka)
10 May-21:34:36 Re: don lum collection (Don Lum)
10 May-12:52:14 Re: a mineralogical trip through germany / baden-wuerttemberg (Jesse Fisher)
10 May-12:23:01 Re: soon 15 years of fmf and how to achieve many more (Makokerowill)
09 May-23:10:51 Re: magnetic serpentine? (Ken)
09 May-11:45:05 Re: collection of michael shaw (Michael Shaw)
09 May-11:22:06 Re: collection of firmo espinar (Firmo Espinar)
08 May-11:32:22 Re: hillman hall of minerals and gems (Tom Mazanec)
08 May-02:15:29 Re: magnetic serpentine? (Alfredo)
08 May-00:00:15 Re: monthly mineral chronicles, mineral guides and more... (Crocoite)
07 May-21:45:34 Magnetic serpentine? (Ken)
07 May-13:00:12 Re: collection of benjamin carballo (Benj)
07 May-07:03:24 Re: collection of david carter (Jordi Fabre)
07 May-06:44:30 Re: collection of david carter (David916)
07 May-06:36:35 Re: collection of benjamin carballo (Benj)
07 May-06:29:30 Re: collection of david carter (David916)
06 May-19:49:56 Re: the mizunaka collection - quartz over chrysocolla (Am Mizunaka)
06 May-14:33:39 Re: a mineralogical trip through italy by sante celiberti (Sante Celiberti)
06 May-10:24:20 Re: collection of david carter (David916)

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  Topic: Calcite form
Josele

Replies: 6
Views: 592

PostForum: Minerals and Mineralogy   Posted: Apr 26, 2021 11:17   Subject: Re: Calcite form
Thanks for these impressive calcite data. I suppose calcite is the specie with the largest number of documented combinations of basic forms. Is that true? More than fluorite?

This is another remark ...
  Topic: Calcite form
Josele

Replies: 6
Views: 592

PostForum: Minerals and Mineralogy   Posted: Apr 25, 2021 15:53   Subject: Re: Calcite form
Thanks for your comments.

A calcite dedicated page that for sure you know well was a great help for determining most common steep scalenohedron forms: http://nsminerals.atspace.com/calcite.html

...
  Topic: Calcite form
Josele

Replies: 6
Views: 592

PostForum: Minerals and Mineralogy   Posted: Apr 25, 2021 10:19   Subject: Calcite form
I've been trying to determine Miller indices of a calcite specimen from Iraí, Brazil. I think it could be a combination of very steep rhombohedron, something like {0.16.1}, finished by the flat rhombo ...
  Topic: Synthetic smoky quartz?
Josele

Replies: 11
Views: 821

PostForum: Minerals and Mineralogy   Posted: Apr 11, 2021 16:14   Subject: Re: Synthetic smoky quartz?
I think it is a lab grown quartz.

There are many offers of this stuff in ebay, Sellers says it is natural but...
  Topic: In-situ photos at Pizzo Forno, Alpe Sponda (Ticino) ?
Josele

Replies: 7
Views: 1375

PostForum: Mines and Mineral Localities   Posted: Mar 16, 2021 15:58   Subject: Re: In-situ photos at Pizzo Forno, Alpe Sponda (Ticino) ?
There are some in Mindat:
https://www.mindat.org/gallery.php?pco=2&loc=3222
  Topic: Schorl
Josele

Replies: 10
Views: 2521

PostForum: Micros & Macros - Images of Minerals   Posted: Jan 17, 2021 17:33   Subject: Re: Schorl
Jim, no problem, we all are amateurs here, even those with high mineralogical level they have something to learn.

In addition to difficult determination of the species in tourmaline group, it often ...
  Topic: Who can help me
Josele

Replies: 26
Views: 10345

PostForum: FOR BEGINNERS: What is it? Where is it from?   Posted: Dec 03, 2020 13:48   Subject: Re: Who can help me
Check hardness trying to scratch a bottle glass. Then clean with your finger and make sure there is a permanent scratch on glass. If so you have some sort of quartz.

And please read instructions an ...
  Topic: What is this?
Josele

Replies: 11
Views: 1868

PostForum: FOR BEGINNERS: What is it? Where is it from?   Posted: Nov 15, 2020 09:56   Subject: Re: What is this?
Carbonates only react to sulphuric acid, although in different ways. Pyrite, being a sulphide, doesn't. ...
Sante, i suppose you mean chlorhydric acid, isn't it?
I never checked the reaction of carb ...
  Topic: What is this?
Josele

Replies: 11
Views: 1868

PostForum: FOR BEGINNERS: What is it? Where is it from?   Posted: Nov 15, 2020 05:18   Subject: Re: What is this?
Looks like pyrite on a quartz vein in a kind of metamorphic rock.
  Topic: Iceland Spar Discontinuity
Josele

Replies: 8
Views: 2426

PostForum: Minerals and Mineralogy   Posted: Nov 14, 2020 12:31   Subject: Re: Iceland Spar Discontinuity
From what I have been able to understand reading related articles, calcite mechanical twinning occurs repeatedly creating multiple lamellar structure. I don't know if this phenomenon has something to ...
  Topic: Iceland Spar Discontinuity
Josele

Replies: 8
Views: 2426

PostForum: Minerals and Mineralogy   Posted: Nov 11, 2020 08:31   Subject: Re: Iceland Spar Discontinuity
Bob, thanks for notice this, I was not aware of this kind of calcite twinning.

In my sample the only one discontinuity runs parallel to the bisector of the rhomb obtuse angle while in your example ...
  Topic: Iceland Spar Discontinuity
Josele

Replies: 8
Views: 2426

PostForum: Minerals and Mineralogy   Posted: Nov 09, 2020 06:11   Subject: Re: Iceland Spar Discontinuity
Thanks for the answers. As Sante said, my doubts concern to the dislocation, discontinuity or whatever it is the "anomaly" that crosses the sample.
If it were in a position not related to c ...
  Topic: Iceland Spar Discontinuity
Josele

Replies: 8
Views: 2426

PostForum: Minerals and Mineralogy   Posted: Nov 07, 2020 17:48   Subject: Iceland Spar Discontinuity
Iceland spar and its amazing birefringence have been the beginning of many mineral vocations, mine among them. Children perceive it as something magic, intriguing enough to wake up interest in crystal ...
  Topic: Cylindrical calcite crystal?
Josele

Replies: 5
Views: 2476

PostForum: Minerals and Mineralogy   Posted: Nov 04, 2020 06:36   Subject: Re: Cylindrical calcite crystal?
Termination seems to be rhombohedral, maybe {021} or {401}. Not well seen in pictures but looks like it has at least another small rhombohedral face at termination.
Could not be an aggregate of small ...
  Topic: Very steep rhombohedral calcite?
Josele

Replies: 14
Views: 3902

PostForum: Minerals and Mineralogy   Posted: Oct 15, 2020 06:16   Subject: Very steep rhombohedral calcite? - Polarity
Rummaging through the drawers I found a Chinese calcite with likely the same flat and steep rhombohedra combination. Crystals up to 2 cm allowed to measure some angles that point to steep rhombohedral ...
  Topic: Very steep rhombohedral calcite?
Josele

Replies: 14
Views: 3902

PostForum: Minerals and Mineralogy   Posted: Oct 07, 2020 11:01   Subject: Re: Very steep rhombohedral calcite?
Bob, thanks for your comment.

Amir, thank you for note the a:c relation in calcite. Smorf must upgrade this unit cell data.

Pete, thanks for notice the positive - negative combination. My last ...
  Topic: Very steep rhombohedral calcite?
Josele

Replies: 14
Views: 3902

PostForum: Minerals and Mineralogy   Posted: Oct 06, 2020 05:10   Subject: Re: Very steep rhombohedral calcite?
Thank you for answering. Special thanks to Pete for his so well exposed reasoning. Is a pleasure read your comments and follow your approach to the matter. I always learn much more than a couple of th ...
  Topic: Very steep rhombohedral calcite?
Josele

Replies: 14
Views: 3902

PostForum: Minerals and Mineralogy   Posted: Oct 05, 2020 09:58   Subject: Very steep rhombohedral calcite?
This crystal was listed in Mindat as "scalenohedral and flat rhombohedral form". Somebody noticed that this description is wrong and it was changed to "steep and flat rhombohedral form& ...
  Topic: New technology for crystal models
Josele

Replies: 3
Views: 2410

PostForum: Off-Topic and Introductions   Posted: Jul 07, 2020 17:55   Subject: Re: New technology for crystal models
In Spanish FMF there is a thread about these crystal models: Modelos cristalográficos
(If you are not comfortable with Spanish can use Google translator at top left of the page)
  Topic: Tourmaline
Josele

Replies: 16
Views: 4332

PostForum: FOR BEGINNERS: What is it? Where is it from?   Posted: Jul 05, 2020 19:44   Subject: Re: Tourmaline
And the two poles are different.
Not necessarily. Although tourmaline belongs to 3m class of the trigonal system and does not have a symmetry center nor symmetry plane perpendicular to the c-axis, it ...
 
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