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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.
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| Search found 144 matches |
| Author | Message |
|---|---|
 Topic: Libyan Desert Glass Structure |
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| marco campos-venuti Replies: 60 Views: 95294 |
 Forum: 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 |
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| marco campos-venuti Replies: 60 Views: 95294 |
Forum: 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". |
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| Topic: Libyan Desert Glass Structure |
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| marco campos-venuti Replies: 60 Views: 95294 |
Forum: 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 |
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| marco campos-venuti Replies: 60 Views: 95294 |
Forum: 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 |
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| marco campos-venuti Replies: 60 Views: 95294 |
Forum: 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 ... |
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| Topic: Gwindel Skutterudite? |
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| marco campos-venuti Replies: 3 Views: 1244 |
Forum: 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 ... |
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| Topic: Gwindel Skutterudite? |
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| marco campos-venuti Replies: 3 Views: 1244 |
Forum: 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 |
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| marco campos-venuti Replies: 7 Views: 2951 |
Forum: 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 |
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| marco campos-venuti Replies: 7 Views: 2951 |
Forum: 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 |
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| marco campos-venuti Replies: 16 Views: 22329 |
Forum: 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. |
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| Topic: cristobalite vs chalcedony in thin section |
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| marco campos-venuti Replies: 16 Views: 22329 |
Forum: 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 ... |
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| Topic: cristobalite vs chalcedony in thin section |
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| marco campos-venuti Replies: 16 Views: 22329 |
Forum: 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 ... |
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| Topic: cristobalite vs chalcedony in thin section |
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| marco campos-venuti Replies: 16 Views: 22329 |
Forum: 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 |
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| marco campos-venuti Replies: 16 Views: 22329 |
Forum: 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 |
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| marco campos-venuti Replies: 16 Views: 22329 |
Forum: 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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