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16 Jul-17:31:41 The mizunaka collection - chalcoalumite (Am Mizunaka)
16 Jul-12:44:28 Architectural spinel from vietnam / #mvm (minerals - virtual museum) collection (Jordi Fabre)
16 Jul-12:18:23 New book: minerals of britain and ireland 2009-2024 - a review (Jordi Fabre)
16 Jul-09:38:43 Re: collection of michael shaw (Michael Shaw)
15 Jul-13:05:10 Sphalerite with calcite from Áliva, spain / #mvm (minerals - virtual museum) collection (Jordi Fabre)
15 Jul-11:32:34 Goesdorf mine (luxembourg) antimony (Roger Warin)
14 Jul-18:03:59 Malachite after azurite on goethite (Silvia)
14 Jul-16:43:05 The mizunaka collection - quartz (Am Mizunaka)
14 Jul-09:34:45 Re: collection of michael shaw (Michael Shaw)
13 Jul-12:19:45 Lazurite (lapis lazuli) from afghanistan / #mvm (minerals - virtual museum) collection (Jordi Fabre)
12 Jul-23:04:14 Re: collection of volkmar stingl (Volkmar Stingl)
12 Jul-09:00:56 Re: the mim museum in beirut, lebanon (Mim Museum)
12 Jul-06:59:21 Re: collection from dany mabillard (Dany Mabillard)
12 Jul-00:49:24 Re: are there pyrite balls found in verzino? (Herwig)
12 Jul-00:25:14 Re: are there pyrite balls found in verzino? (Roger Warin)
12 Jul-00:08:38 Re: are there pyrite balls found in verzino? (Roger Warin)
11 Jul-17:36:07 The mizunaka collection - fluorite (Am Mizunaka)
11 Jul-14:14:25 Re: slice schalenblende (Mathias)
11 Jul-14:08:21 Re: czech rockhounding adventures – agates & amethysts (Stoner)
11 Jul-08:12:55 Czech rockhounding adventures – agates & amethysts (Stoner)
11 Jul-08:03:52 Re: are there pyrite balls found in verzino? (James Catmur)
11 Jul-02:33:28 Re: collection of michael shaw (Michael Shaw)
11 Jul-00:24:28 Re: collection of volkmar stingl (Volkmar Stingl)
10 Jul-13:46:07 Re: are there pyrite balls found in verzino? (Dany Mabillard)
10 Jul-13:45:53 Veszelyite from sanguozhuang, china / #mvm (minerals - virtual museum) collection (Jordi Fabre)

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  Topic: Libyan Desert Glass Structure
marco campos-venuti

Replies: 60
Views: 95294

PostForum: Minerals and Mineralogy   Posted: Jul 02, 2025 10:06   Subject: Re: Libyan Desert Glass Structure
I see epigenetic inclusions in LDG_14, not leaves.
  Topic: Libyan Desert Glass Structure
marco campos-venuti

Replies: 60
Views: 95294

PostForum: Minerals and Mineralogy   Posted: Jul 02, 2025 09:12   Subject: Re: Libyan Desert Glass Structure
An impression is a fossil.
Absolutely not. And first of all you have to demonstrate the impression of what it is. I do not see any biological structure in your "impressions".
  Topic: Libyan Desert Glass Structure
marco campos-venuti

Replies: 60
Views: 95294

PostForum: Minerals and Mineralogy   Posted: Jul 02, 2025 08:49   Subject: Re: Libyan Desert Glass Structure
The presence of carbon and some organic molecules does not mean that they are fossils. No primary biological structure has been found.
  Topic: Libyan Desert Glass Structure
marco campos-venuti

Replies: 60
Views: 95294

PostForum: Minerals and Mineralogy   Posted: Jun 30, 2025 14:39   Subject: Re: Libyan Desert Glass Structure
Still the ignition temperature of a seed is in the order of 2-300 C and melting point of glass is around 800 C.
  Topic: Libyan Desert Glass Structure
marco campos-venuti

Replies: 60
Views: 95294

PostForum: Minerals and Mineralogy   Posted: Jun 30, 2025 12:24   Subject: Re: Libyan Desert Glass Structure
Dear Craig, I admire the perseverance and illusion you put into your study.
However, you cannot hunt for fossils inside a glass that was formed at temperatures estimated to be above 2750°C. If the ro ...
  Topic: Gwindel Skutterudite?
marco campos-venuti

Replies: 3
Views: 1244

PostForum: Minerals and Mineralogy   Posted: Jun 30, 2025 12:07   Subject: Re: Gwindel Skutterudite?
Dear Roger and Pete, thank you for your comments. The title of the post was intentionally provocative. However, I would like to open the controversy.
Mindat clearly says that "any gwindel is nec ...
  Topic: Gwindel Skutterudite?
marco campos-venuti

Replies: 3
Views: 1244

PostForum: Minerals and Mineralogy   Posted: Jun 28, 2025 14:11   Subject: Gwindel Skutterudite?
A curiosity I found in Sainte Marie this year. This skutterudite crystal from Bou Azzer is twisted. It was a typical Moroccan lot consisting of a box with at least 30 crystals and all of them showed t ...
  Topic: Ghost dendrite
marco campos-venuti

Replies: 7
Views: 2951

PostForum: Minerals and Mineralogy   Posted: May 03, 2025 04:17   Subject: Re: Ghost dendrite
I show you the back of the cabochon made of white opal. The dendrite is all inside. This is the drawer where it has been for 13 years. The only change was the addition of the azurite and malachite sam ...
  Topic: Ghost dendrite
marco campos-venuti

Replies: 7
Views: 2951

PostForum: Minerals and Mineralogy   Posted: May 02, 2025 02:20   Subject: Ghost dendrite
Years ago I cut a beautiful clear opal cabochon with a beautiful well-centered black dendrite. The best quality of that cabochon was that it was from Cabo de Gata, Almeria, Spain a little-known locati ...
  Topic: cristobalite vs chalcedony in thin section
marco campos-venuti

Replies: 16
Views: 22329

PostForum: Minerals and Mineralogy   Posted: Apr 09, 2025 13:24   Subject: Re: cristobalite vs chalcedony in thin section
Sorry Alfredo,
my comment comes from the fact that gypsum does not appear on the mindat page. Maybe you can add it.
  Topic: cristobalite vs chalcedony in thin section
marco campos-venuti

Replies: 16
Views: 22329

PostForum: Minerals and Mineralogy   Posted: Apr 09, 2025 06:32   Subject: Re: cristobalite vs chalcedony in thin section
Hi Alfredo,
perhaps you are referring to the gypsum of Mina Rica, Pulpì, Almeria, Spain, where gypsum crystals show inclusions of celestine needles and white spherulites. In my opinion, in that case ...
  Topic: cristobalite vs chalcedony in thin section
marco campos-venuti

Replies: 16
Views: 22329

PostForum: Minerals and Mineralogy   Posted: Apr 08, 2025 10:16   Subject: Re: cristobalite vs chalcedony in thin section
Hi Daniel,
From the hand sample the chalcedony is spherical and I don't see any faces. From the last photo you can see chalcedony filling a cavity inside a gypsum crystal, but I still don't see any f ...
  Topic: cristobalite vs chalcedony in thin section
marco campos-venuti

Replies: 16
Views: 22329

PostForum: Minerals and Mineralogy   Posted: Apr 08, 2025 07:59   Subject: Re: cristobalite vs chalcedony in thin section
I don't see replacing after gypsum. The formation of your spherulites looks like the growth of a concretion. There is a granular gypsum with porosity. A Si-rich solution flows through the porosity. Th ...
  Topic: cristobalite vs chalcedony in thin section
marco campos-venuti

Replies: 16
Views: 22329

PostForum: Minerals and Mineralogy   Posted: Apr 08, 2025 05:38   Subject: Re: cristobalite vs chalcedony in thin section
My impression is that it is all chalcedony. Chalcedony is a fibrous silica polymer so the structure you see in thin section looks very similar to it. Cristobalite is stable over 1470ºC, Therefore it i ...
  Topic: cristobalite vs chalcedony in thin section
marco campos-venuti

Replies: 16
Views: 22329

PostForum: Minerals and Mineralogy   Posted: Apr 08, 2025 03:40   Subject: Re: cristobalite vs chalcedony in thin section
Cristobalite is high T mineral. All supposed cristobalite spherulites are other silica phase.
 
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