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A general guide for using the Forum with some rules and tips
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 15 matches |
| Author | Message |
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 Topic: Pyrite with bubble-like growths |
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| Dean Allum Replies: 21 Views: 24796 |
 Forum: Minerals and Mineralogy Posted: Jan 17, 2021 23:39 Subject: Re: Pyrite with bubble-like growths |
| Pete,
After reading this article, I have another theory for you to consider. Epitaxial marcasite on pyrite from Rensselaer, Indiana -K. J. Brock; L. D. Slater American Mineralogist (1978) 63 (1-2 ... |
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| Topic: Pyrite with bubble-like growths |
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| Dean Allum Replies: 21 Views: 24796 |
Forum: Minerals and Mineralogy Posted: Jan 05, 2021 22:03 Subject: Re: Pyrite with bubble-like growths |
| Pete,
Thank you for posting this fun puzzle for us to think about over the holidays. 1) I own many spherical pyrite concretions formed in a limestone environment, nucleating on organic matter. Is ... |
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| Topic: Sainte Marie-aux-Mines Show 2013 - 50th Edition! |
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| Dean Allum Replies: 65 Views: 197678 |
Forum: News about Shows Posted: Jul 03, 2013 14:38 Subject: Re: Sainte Marie-aux-Mines Show 2013 - 50th Edition! |
| Fred, Jordi, Roger,
All these photographs are magnificent by themselves. The fact that they were taken through glass, and the reflections are negligible makes them miraculous. Thank you. -Dean |
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| Topic: About cyclic twinning - (5) |
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| Dean Allum Replies: 157 Views: 340585 |
Forum: Featured Columns of FMF Posted: Jan 12, 2013 16:12 Subject: Re: About cyclic twinning - (5) |
| James,
Nice post! That hole appears to be a flat spot in a concave recess. Do you know that it extends all the way through the specimen? Pete, A cyclic twin with a hole in the center (similar to ... |
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| Topic: Mica Twins |
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| Dean Allum Replies: 13 Views: 38452 |
Forum: Minerals and Mineralogy Posted: Oct 28, 2012 17:05 Subject: Re: Mica Twins |
| These "A-type" muscovite books are common in Fremont and Park county pegmatites in Colorado. Several local collectors think these are a type of twin, but now I am not sure. Notice that the A ... | |
| Topic: About cyclic twinning - (5) |
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| Dean Allum Replies: 157 Views: 340585 |
Forum: Featured Columns of FMF Posted: Oct 04, 2012 21:57 Subject: Re: About cyclic twinning - (5) |
| Wow, I was just about post a question about the atomic origins of crystal twinning.
Elise, Do you have a pdf copy of that nanoLetters paper? Regards, Dean ALlum |
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| Topic: About cyclic twinning - (5) |
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| Dean Allum Replies: 157 Views: 340585 |
Forum: Featured Columns of FMF Posted: Aug 20, 2012 23:56 Subject: Re: About cyclic twinning - (5) |
| Pete,
Your competing poly-crystals theory for cyclic twinning is elegant! Wouldn't there be some remaining evidence of the nucleation site at the central vertex which you could view with a TEM of ... |
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| Topic: About cyclic twinning - (5) |
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| Dean Allum Replies: 157 Views: 340585 |
Forum: Featured Columns of FMF Posted: Aug 20, 2012 13:09 Subject: Re: About cyclic twinning - (5) |
| Pete,
Your competing poly-crystals theory for cyclic twinning is elegant! Wouldn't there be some remaining evidence of the nucleation site at the central vertex which you could view with a TEM of ... |
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| Topic: Colorado School of Mines Geology Museum |
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| Dean Allum Replies: 19 Views: 86261 |
Forum: Colorado School of Mines Geology Museum Posted: Jun 14, 2012 11:02 Subject: Re: Colorado School of Mines Geology Museum |
| I can't believe there were no pictures of perhaps the second best mineral exhibit of all time!
Collections manager, Ed Raines, has put together a showcase of Colorado Rare Earth minerals. This Glor ... |
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| Topic: What makes a great mineral collector? |
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| Dean Allum Replies: 21 Views: 51881 |
Forum: The histories behind mineral specimens Posted: Mar 16, 2012 13:27 Subject: Re: What makes a great mineral collector? |
| David,
Let's try out some of the responses to real world "Great Collectors". Here is a short list of legendary collectors which most people would classify as "great". James Sm ... |
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| Topic: The end of mineral collecting |
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| Dean Allum Replies: 14 Views: 25450 |
Forum: Off-Topic and Introductions Posted: Nov 04, 2011 11:36 Subject: Re: The end of mineral collecting |
| The concept of running out of mineral specimens is so foreign to me.
I regularly visit old mine sites in the Rocky Mountains having abundant dumps. They appear to have not been visited for decades ... |
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| Topic: Gail Spann's HOUSTON 2010 show report |
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| Dean Allum Replies: 122 Views: 221850 |
Forum: Mineral Shows by Gail Spann Posted: May 07, 2010 16:25 Subject: Re: Gail Spann's HOUSTON 2010 show report |
| Gail,
Now that you and Jim are in the market for a set of bowling pins, have you seen this? https://www.mindat.org/photo-58452.html -Dean Allum |
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| Topic: The Arizona Issue |
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| Dean Allum Replies: 14 Views: 26078 |
Forum: Off-Topic and Introductions Posted: Apr 30, 2010 14:13 Subject: Re: The Arizona Issue |
| Phil,
Exactly which legislative initiative in Arizona are you talking about? Then, what do you believe is the motivation of Arizonans for passing this legislation? -Dean |
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| Topic: Large red beryl crystal..when quantity compares with quality |
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| Dean Allum Replies: 7 Views: 17149 |
Forum: Minerals and Mineralogy Posted: Feb 21, 2010 19:35 Subject: Re: Large red beryl crystal..when quantity compares with quality |
| amethystguy,
I usually go for quantity over perceived quality. The rocks that we typically deal with are unusual in nature. It is more unusual to have a large rock than a perfectly formed microscopic ... |
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| Topic: Rose Quartz - Single crystal or not? |
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| Dean Allum Replies: 16 Views: 31805 |
Forum: Minerals and Mineralogy Posted: Jan 28, 2010 13:14 Subject: Re: Rose Quartz - Single crystal or not? |
| Duncan,
I created that setup and saw 4-extinctions per 360 degree rotation when the Z-axis was perpendicular to the light. This setup does not appear to work if the surface is frosted or there are ... |
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