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Newest topics and users posts
02 Jul-14:58:25 The mizunaka collection - calcite with pyrite (Am Mizunaka)
02 Jul-14:44:48 Sainte-marie-aux-mines 2022 - the new discoveries (1) (Jordi Fabre)
01 Jul-16:16:08 Re: pyromorphite and ...? (Colin Robinson)
01 Jul-13:56:47 Re: twinned topaz? (John S. White)
01 Jul-12:20:34 Re: pyromorphite and ...? (Forrestblyth)
01 Jul-11:34:01 Re: caldbeck cumbria mineral (Forrestblyth)
01 Jul-11:25:31 Re: pyromorphite and ...? (Forrestblyth)
01 Jul-10:32:27 Re: twinned topaz? (Bob Carnein)
01 Jul-10:17:29 Re: collection of volkmar stingl (Volkmar Stingl)
01 Jul-10:15:24 Re: twinned topaz? (Yannick Cosson)
01 Jul-08:51:24 Re: twinned topaz? (Pete Richards)
01 Jul-07:43:29 Re: twinned topaz? (Josele)
01 Jul-06:38:46 Re: twinned topaz? (Bob Morgan)
01 Jul-05:07:43 Twinned topaz? (Yannick Cosson)
30 Jun-23:13:16 The mizunaka collection - fluorite (Am Mizunaka)
30 Jun-16:35:12 Re: pyromorphite and ...? (Colin Robinson)
30 Jun-16:29:27 Re: collection of firmo espinar (Firmo Espinar)
30 Jun-16:27:07 Re: linarite (Colin Robinson)
30 Jun-16:18:29 Re: barytocalcite (Colin Robinson)
30 Jun-14:20:08 Re: spherical inclusions in amethyst - cristobalite? vs fluorite (Roger Warin)
30 Jun-14:06:03 Re: spherical inclusions in amethyst - cristobalite? vs fluorite (Amir Akhavan)
30 Jun-08:05:23 Baryte (Forrestblyth)
30 Jun-07:58:42 Barytocalcite (Forrestblyth)
30 Jun-07:50:45 Re: caldbeck cumbria mineral (Kevin Schofield)
30 Jun-07:49:05 Baryte (Forrestblyth)

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  Topic: Tourmaline - Quartz epitaxy?
marco campos-venuti

Replies: 7
Views: 987

PostForum: Minerals and Mineralogy   Posted: Apr 23, 2022 06:02   Subject: Re: Tourmaline - Quartz epitaxy?
The pocket contained several hundred crystals, all with their respective tourmaline in the center and with the same orientation. I had the opportunity to measure some of them and they all gave values ...
  Topic: Forms Involved in Titanite Crystal
marco campos-venuti

Replies: 19
Views: 3130

PostForum: Minerals and Mineralogy   Posted: Apr 22, 2022 14:58   Subject: Re: Forms Involved in Titanite Crystal
I have an untwinned single crystal of titanite from that area. I had it as from Mohmand Agency, Pakistan, not really near, but you know stones in these mountains walk with nomad peoples. It has many s ...
  Topic: Tourmaline - Quartz epitaxy?
marco campos-venuti

Replies: 7
Views: 987

PostForum: Minerals and Mineralogy   Posted: Apr 22, 2022 14:12   Subject: Re: Tourmaline - quartz epitaxy?
In a paper published years ago, I suggested the possibility of quartz epitaxy after tourmaline at an angle of 23.5°. I took these data from a group of quartz crystals probably found in Morro Redondo, ...
  Topic: Minerals and mysteries from a college collection
marco campos-venuti

Replies: 9
Views: 2935

PostForum: What is it? - Where is it from?   Posted: Oct 20, 2021 06:20   Subject: Re: Minerals and mysteries from a college collection
There are many minerals making nodules with the same fabric. Barite also is a good guess, you can check density.
  Topic: April shows in Tucson??
marco campos-venuti

Replies: 10
Views: 6874

PostForum: Mineral Shows by Gail Spann   Posted: Dec 16, 2020 12:26   Subject: Re: April shows in Tucson??
GJX is not planning on having an April show as they "feel things won’t be much different than they are now".
  Topic: Interesting find, opalized scoria from oregon
marco campos-venuti

Replies: 1
Views: 2206

PostForum: What is it? - Where is it from?   Posted: Sep 18, 2020 05:31   Subject: Re: Interesting find, opalized scoria from oregon
Scorias are often filled by silica because cavities drain water. It is difficult to find empty cavities in old scorias from the geological record. More often they are filled by something, zeolites, ca ...
  Topic: Quartz and Humboldtine? from Colombia
marco campos-venuti

Replies: 16
Views: 16975

PostForum: Minerals and Mineralogy   Posted: Oct 07, 2018 12:20   Subject: Re: Quartz and Humboldtine? from Colombia
I bought this in 2006, supposedly from Brazil. It looks so similar!
Here the yellow appears to be inside. The vermicular growth reminds me of chlorite family minerals. The yellow is brighter in real ...
  Topic: Who to trust with gemstone identification? Are some gemologists better than others?
marco campos-venuti

Replies: 11
Views: 16295

PostForum: Incorrect classification and fakes   Posted: Sep 07, 2018 06:28   Subject: Re: Who to trust with gemstone identification? Are some gemologists better than others?
The distinction from natural citrine and heat treated amethyst is possible with expensive test in a high tech laboratory. Because citrine is a cheap stone, dealers assume all citrine in the market are ...
  Topic: Termination in a tourmaline crystal
marco campos-venuti

Replies: 2
Views: 4800

PostForum: Minerals and Mineralogy   Posted: Aug 28, 2018 08:37   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 symm ...
  Topic: Abrasives repairing polishing crystals
marco campos-venuti

Replies: 11
Views: 11101

PostForum: Conserving, Preparing and Cleaning Minerals   Posted: Aug 18, 2018 17:34   Subject: Re: Abrasives repairing polishing crystals
Of course natural is better as for hair, nose, breast, etc. But in some cases you want to save a specimen. Because of sentiment, because it is very valuable or because it is an educational specimen. I ...
  Topic: Agates in Sicily?
marco campos-venuti

Replies: 9
Views: 17232

PostForum: Rockhounding trips   Posted: Apr 25, 2018 11:16   Subject: Re: Agates in Sicily
Bad News Alan, no agates in Sicily!!!
Despite the tradition wants that the name agate comes from the old name of the Drillo River, a small creek passing near Etna Volcano, there was probably a big hi ...
  Topic: Faden Quartz Crystals - (26)
marco campos-venuti

Replies: 63
Views: 84025

PostForum: Featured Columns of FMF   Posted: Dec 15, 2017 11:28   Subject: Re: Faden Quartz Crystals - (26)
Hi Roger,
I consider we are at the same side of the theories, as anti-official. But something in your discussion sounds strange to me.
A gel is a solid and for that reason can't have viscosity that ...
  Topic: Information about a Rhodochrosite specimen
marco campos-venuti

Replies: 3
Views: 6603

PostForum: Minerals and Mineralogy   Posted: Nov 18, 2017 09:16   Subject: Re: Information about a Rhodochrosite specimen
Check mindat:
https://www.mindat.org/photo-519101.html
Wutong Mine (Wudong Mine), Liubao, Cangwu Co., Wuzhou Prefecture, Guangxi Zhuang Autonomous Region, China
  Topic: Micro photos of inclusions in Quartz
marco campos-venuti

Replies: 108
Views: 103461

PostForum: Micros & Macros - Images of Minerals   Posted: Nov 14, 2017 06:50   Subject: Re: Micro photos of inclusions in Quartz
I have one sample of the blue inclusion. I'm not sure it is natural or synthetic quartz. No info about any deposit.
  Topic: Super thin hematite inclusions in amethyst
marco campos-venuti

Replies: 22
Views: 25034

PostForum: Micros & Macros - Images of Minerals   Posted: Nov 13, 2017 04:21   Subject: Re: Super thin hematite inclusions in amethyst
It is from Rome!
(We are joking, come back to the topic please)
  Topic: Super thin hematite inclusions in amethyst
marco campos-venuti

Replies: 22
Views: 25034

PostForum: Micros & Macros - Images of Minerals   Posted: Nov 12, 2017 12:44   Subject: Re: Super thin hematite inclusions in amethyst
And here is what we call Quartz with iron oxides, because we don't know what it really is. Also from Minas Gerais
  Topic: Super thin hematite inclusions in amethyst
marco campos-venuti

Replies: 22
Views: 25034

PostForum: Micros & Macros - Images of Minerals   Posted: Nov 12, 2017 12:41   Subject: Re: Super thin hematite inclusions in amethyst
And here few examples of what I consider Goethite in Quartz. I'm not sure, just is what I use to call it. Mostly yellow and strictly fibrous, more abundant in Amethyst. All samples from Brazil.
The l ...
  Topic: Super thin hematite inclusions in amethyst
marco campos-venuti

Replies: 22
Views: 25034

PostForum: Micros & Macros - Images of Minerals   Posted: Nov 12, 2017 12:31   Subject: Re: Super thin hematite inclusions in amethyst
Few examples of what I suppose is Hematite in Quartz. Mostly red, main characteristic is a flat crystal, more or less elongated.
All sample are from Brazil, difficult to say the exact place. How woul ...
  Topic: Super thin hematite inclusions in amethyst
marco campos-venuti

Replies: 22
Views: 25034

PostForum: Micros & Macros - Images of Minerals   Posted: Nov 12, 2017 12:18   Subject: Re: Super thin hematite inclusions in amethyst
John, is it possible to distinguish fibrous Hematite from fibrous Goethite with the naked eye? I mean not included in quartz but when they are in botryoidal shape. I suspect there is a bit of confusio ...
  Topic: Rarest quartz twins with inclined axes C
marco campos-venuti

Replies: 42
Views: 41387

PostForum: Minerals and Mineralogy   Posted: Nov 08, 2017 20:27   Subject: Re: Rarest quartz twins with inclined axes C
I think auto-epitaxy is a synonym of twinning. Epitaxy is between two different minerals.
If a secondary xl (or a epitaxial film) grows over a main xl, its atoms will continue the lattice of the firs ...
 
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