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| Search found 18 matches |
| Author | Message |
|---|---|
 Topic: Fluorite crystallography? |
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| Johan Kjellman Replies: 27 Views: 10404 |
 Forum: Minerals and Mineralogy Posted: Dec 13, 2023 02:57 Subject: Re: Fluorite crystallography? |
| I agree again - and withdraw my claim.
And Pete, you point directly at what I now think so many of us, although experienced, keep on misinterpreting these combos. We are all fast and confident in ide ... |
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| Topic: Fluorite crystallography? |
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| Johan Kjellman Replies: 27 Views: 10404 |
Forum: Minerals and Mineralogy Posted: Dec 12, 2023 17:58 Subject: Re: Fluorite crystallography? |
| Another Naica fluorite, which according to Pete's analysis would be cube-dodechahedral habit. From the find circa 2005.
I 100 % agree with Pete's analysis of how to differentiate between the two co ... |
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| Topic: Crystallography question |
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| Johan Kjellman Replies: 6 Views: 5200 |
Forum: Minerals and Mineralogy Posted: Jun 17, 2022 03:30 Subject: Re: Crystallography question |
| Check,
Richards 1996 Canadian Mineralogist 34, pp. 615-621. It's on twinned hambergite from Stak Nala and should help you a bit. cheers |
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| Topic: Elbaite, ending moor's head |
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| Johan Kjellman Replies: 9 Views: 7087 |
Forum: Minerals and Mineralogy Posted: Jun 11, 2022 18:31 Subject: Re: Elbaite, ending moor's head |
| Roger,
I think we can agree that the Moor's head signifies an abrupt change in fluid chemistry. A proposed explanation for that abrupt change has been that the pegmatite/pegmatite pocket cracks open ... |
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| Topic: Elbaite, ending moor's head |
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| Johan Kjellman Replies: 9 Views: 7087 |
Forum: Minerals and Mineralogy Posted: Jun 11, 2022 10:40 Subject: Re: Elbaite, ending moor's head |
| Roger,
I hate this, especially those sites where one registered say 5 years ago in order to see or get something, and then come back say 5 years later and try to register (cause one's completely for ... |
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| Topic: Elbaite, ending moor's head |
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| Johan Kjellman Replies: 9 Views: 7087 |
Forum: Minerals and Mineralogy Posted: Jun 10, 2022 15:34 Subject: Re: Elbaite, ending moor's head |
| Federico Pezzotta has at least touched upon similar questions.
Two titles of his: Color anomalies at the termination of pegmatitic gem-tourmaline crystals from Elba Island (Tyrrhenian Sea, Italy): a ... |
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| Topic: More Label Translation |
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| Johan Kjellman Replies: 9 Views: 5869 |
Forum: What is it? - Where is it from? Posted: Jun 10, 2022 05:51 Subject: Re: More Label Translation |
| No worries, I mean no harm, either way the information's out.
cheers |
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| Topic: More Label Translation |
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| Johan Kjellman Replies: 9 Views: 5869 |
Forum: What is it? - Where is it from? Posted: Jun 10, 2022 04:12 Subject: Re: More Label Translation |
| ... it looks like a discussion of the crystal habit, but otherwise I am lost. Thanks in advance!
Jesse, I have attached an answer for you because this "smart" system kicks me out all th ... |
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| Topic: Photos of epitaxy - (16) |
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| Johan Kjellman Replies: 55 Views: 150615 |
Forum: Featured Columns of FMF Posted: Oct 20, 2021 14:47 Subject: Columbite on Samarskite |
| Sample 1998-8184 from Museum für Naturkunde in Berlin, type sample from Gustav Rose. | |
| Topic: Black, metallic, yellow oxide? |
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| Johan Kjellman Replies: 24 Views: 13978 |
Forum: What is it? - Where is it from? Posted: Jul 24, 2021 12:18 Subject: Re: Black, metallic, yellow oxide? |
| I'm debating on the Connecticut provenance though, could also be Rwanda, Uganda... I'm hoping I may be able to tie that down too. You guys have been very helpful. I'm about 95% convinced on the specie ... | |
| Topic: Bob Cook wins the 2021 John S. White Mineral Legacy Award |
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| Johan Kjellman Replies: 2 Views: 13689 |
Forum: The histories behind mineral specimens Posted: May 01, 2021 12:58 Subject: Re: Bob Cook wins the 2021 John S. White Mineral Legacy Award |
| Bobcookite not cookeite!
cheers ____________________________________________ Fixed. Thanks Johan! |
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| Topic: Aragonite "drill bit" twin |
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| Johan Kjellman Replies: 16 Views: 19574 |
Forum: Minerals and Mineralogy Posted: Mar 31, 2020 06:29 Subject: Re: aragonite "drill bit" twin |
| Also, note that Haüy always publish individual images of the separate contributing crystals for the twin formations - each one in its actual orientation. In this case, figures 236-239.
cheers |
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| Topic: Aragonite "drill bit" twin |
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| Johan Kjellman Replies: 16 Views: 19574 |
Forum: Minerals and Mineralogy Posted: Mar 31, 2020 06:26 Subject: Re: aragonite "drill bit" twin |
| Thanks, Johan and Jordi. What I'm seeing in the figure appears to have 2-fold symmetry (2 crystals intergrown). My specimen definitely has 3-fold symmetry around the twin axis. The forms present ap ... | |
| Topic: Aragonite "drill bit" twin |
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| Johan Kjellman Replies: 16 Views: 19574 |
Forum: Minerals and Mineralogy Posted: Mar 30, 2020 15:46 Subject: Re: aragonite "drill bit" twin |
| Thanks. Can you possibly scan that figure? Or is it available on-line (I did a search but was unable to find it).
Bob, I just pm'd you the link as it couldn't be posted here. PM me your email if ... |
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| Topic: Aragonite "drill bit" twin |
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| Johan Kjellman Replies: 16 Views: 19574 |
Forum: Minerals and Mineralogy Posted: Mar 30, 2020 06:22 Subject: Re: aragonite "drill bit" twin |
| Actually, your twin resembles very much figures 234 and 235 on plate 86, the last one in Haüy's atlas from 1801.
cheers |
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| Topic: Malachite twinning |
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| Johan Kjellman Replies: 5 Views: 14187 |
Forum: Minerals and Mineralogy Posted: Mar 08, 2020 06:27 Subject: Re: Malachite twinning |
| Someone claimed that all malachite is twinned.
Does anyone know of any discussion or papers to this effect? Best, Ray Order-disorder twinning of malachite Makovicky, Emil (Institute of Ge ... |
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| Topic: The Joy of Tucson, 2020 Gail Spann Experience |
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| Johan Kjellman Replies: 107 Views: 155866 |
Forum: Mineral Shows by Gail Spann Posted: Feb 05, 2020 11:15 Subject: Re: The Joy of Tucson, 2020 Gail Spann Experience |
| thanks, I figured - there is one "different but the same" on mindat
cheers |
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| Topic: The Joy of Tucson, 2020 Gail Spann Experience |
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| Johan Kjellman Replies: 107 Views: 155866 |
Forum: Mineral Shows by Gail Spann Posted: Feb 05, 2020 04:46 Subject: Re: The Joy of Tucson, 2020 Gail Spann Experience |
| And another view...
Excellent specimen, and a great example of hematite/rutile epitaxy. Is there a more specific location? |
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