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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 117 matches |
| Author | Message |
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 Topic: Fluorite twin mistery |
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| marco campos-venuti Replies: 2 Views: 350 |
 Forum: What is it? - Where is it from? Posted: Apr 03, 2024 13:49 Subject: Fluorite twin mistery |
| We all have drawers full of samples that we don't know what they are. Some day I wake up a little bit Poirot and I start investigating one of those samples, but since I can't solve the mystery, I prop ... | |
| Topic: Dissolution enables dolomite crystal growth near ambient conditions |
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| marco campos-venuti Replies: 9 Views: 4430 |
Forum: Mineralogical Literature Posted: Nov 24, 2023 11:16 Subject: Re: Dissolution enables dolomite crystal growth near ambient conditions |
| Pete I have to contradict you. Your explanation of the replacement of calcite by dolomite during diagenesis was the ancient solution to the origin of dolomite formations such as the Dolomite Mountains ... | |
| Topic: Dissolution enables dolomite crystal growth near ambient conditions |
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| marco campos-venuti Replies: 9 Views: 4430 |
Forum: Mineralogical Literature Posted: Nov 24, 2023 07:27 Subject: Re: Dissolution enables dolomite crystal growth near ambient conditions |
| The "dolomite problem" does not refer to the difficulty of growing crystals in the laboratory, but to its abundance in nature in low temperature environments since dolomite crystallizes in h ... | |
| Topic: Pele's Hair and Tears |
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| marco campos-venuti Replies: 5 Views: 6024 |
Forum: Minerals and Mineralogy Posted: Sep 26, 2023 12:29 Subject: Re: Pele's Hair and Tears |
| Hi Roger,
A normal explosive volcanic eruption produces glass shards called volcanic ash that will form tuff deposits. Even eruptions dominated by lava flows have a short explosive phase at the begin ... |
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| Topic: An idea for a collection |
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| marco campos-venuti Replies: 20 Views: 13906 |
Forum: Minerals and Mineralogy Posted: May 19, 2023 11:38 Subject: Re: An idea for a collection |
| Hi James,
Cotham Marble is a well-known and well-studied stromatolite with dendritic-plumy shapes. The second photo of the cover represents a manganese dendrite, which I theorize precipitated from a ... |
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| Topic: An idea for a collection |
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| marco campos-venuti Replies: 20 Views: 13906 |
Forum: Minerals and Mineralogy Posted: May 19, 2023 11:30 Subject: Re: An idea for a collection |
| Hi Roger,
I am a geologist and I had to document myself to do an interdisciplinary work between geology and biology. This is why I added an initial chapter to the book to explain the basic concepts t ... |
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| Topic: An idea for a collection |
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| marco campos-venuti Replies: 20 Views: 13906 |
Forum: Minerals and Mineralogy Posted: May 18, 2023 08:16 Subject: Re: An idea for a collection |
| About the relationship between mineralogy and biology I recently published a voluminous book entitled "Biominerals: Microbial Life in Agates and other Minerals". In this work I try to identi ... | |
| Topic: Pebbles from Elba, containing... tourmaline? |
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| marco campos-venuti Replies: 4 Views: 8945 |
Forum: What is it? - Where is it from? Posted: Nov 16, 2022 04:11 Subject: Re: Pebbles from Elba, containing... tourmaline? |
| I realized there is an intruder in your pile of rocks. It is a brecciated marl from the Elba Flysch (Cretaceous). The white stripes are of calcite. | |
| Topic: Pebbles from Elba, containing... tourmaline? |
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| marco campos-venuti Replies: 4 Views: 8945 |
Forum: What is it? - Where is it from? Posted: Nov 16, 2022 03:56 Subject: Re: Pebbles from Elba, containing... tourmaline? |
| The pebbles are from Capo Bianco beach, north of the Island, near Portoferraio and are constituted by the Capo bianco aplite dike dated 8.4 My, before the main granodiorite pluton of Monte Capanne dat ... | |
| Topic: Tourmaline - Quartz epitaxy? |
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| marco campos-venuti Replies: 7 Views: 5299 |
Forum: 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 |
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| marco campos-venuti Replies: 19 Views: 11731 |
Forum: 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? |
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| marco campos-venuti Replies: 7 Views: 5299 |
Forum: 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 |
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| marco campos-venuti Replies: 9 Views: 6332 |
Forum: 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?? |
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| marco campos-venuti Replies: 10 Views: 11749 |
Forum: 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 |
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| marco campos-venuti Replies: 1 Views: 3217 |
Forum: 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 |
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| marco campos-venuti Replies: 16 Views: 24183 |
Forum: 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 ... |
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| Topic: Who to trust with gemstone identification? Are some gemologists better than others? |
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| marco campos-venuti Replies: 11 Views: 21032 |
Forum: 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 |
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| marco campos-venuti Replies: 2 Views: 5998 |
Forum: 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 |
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| marco campos-venuti Replies: 11 Views: 15509 |
Forum: 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? |
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| marco campos-venuti Replies: 9 Views: 22579 |
Forum: 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 ... |
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