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Newest topics and users posts
25 Oct-08:29:19 Re: don lum collection (Don Lum)
25 Oct-07:01:21 Re: new generation for picture - ploum (Ploum)
25 Oct-06:02:47 Re: new generation for picture - ploum (Ploum)
25 Oct-01:41:28 Re: collection of michael shaw (Tobi)
25 Oct-01:37:51 Re: collection of sante celiberti (Tobi)
25 Oct-01:34:43 Re: silvia's collection (Tobi)
25 Oct-01:32:18 Re: don lum collection (Tobi)
25 Oct-01:26:48 Re: collection of tobi (Tobi)
24 Oct-23:42:01 Re: collection of volkmar stingl (Volkmar Stingl)
24 Oct-21:41:08 Re: don lum collection (Don Lum)
24 Oct-21:40:15 Re: the mizunaka collection - quartz (Am Mizunaka)
24 Oct-20:05:46 Silvia's collection - huge siderite (Silvia)
24 Oct-19:57:24 Re: the mizunaka collection - quartz (Silvia)
24 Oct-18:44:45 The mizunaka collection - quartz (Am Mizunaka)
24 Oct-15:15:23 Re: collection of sante celiberti (Sante Celiberti)
24 Oct-14:52:30 Re: collection of michael shaw (Michael Shaw)
24 Oct-13:43:08 Re: collection of michael shaw (Silvia)
24 Oct-11:17:10 Re: collection of michael shaw (Michael Shaw)
24 Oct-09:37:12 Re: collection of volkmar stingl (Volkmar Stingl)
24 Oct-09:28:16 Re: collection of michael shaw (Volkmar Stingl)
24 Oct-09:04:01 Re: collection of michael shaw (Michael Shaw)
24 Oct-03:54:43 Re: collection of tobi (Dany Mabillard)
24 Oct-03:50:24 Re: collection of tobi (Tobi)
23 Oct-23:28:11 Re: help found with items (Philippe Durand)
23 Oct-15:08:16 Silvia's collection - classic portugese ferberite (Silvia)

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  Topic: Alleged 'silvers' from Udokan?
alfredo

Replies: 5
Views: 507

PostForum: Off-Topic and Introductions   Posted: Oct 14, 2021 06:03   Subject: Re: Alleged 'silvers' from Udokan?
This reminds me of a recent case from Germany where a dealer made a lot of money selling large pieces of "native brass", zhanghengite, and other extremely rare copper-zinc alloys in previous ...
  Topic: Conditions where pyrite/pyritohedra are formed
alfredo

Replies: 16
Views: 1246

PostForum: Minerals and Mineralogy   Posted: Oct 05, 2021 05:40   Subject: Re: Conditions where pyrite/pyritohedra are formed
Not about pyrite, but I have a very similar old study about galena crystal habits. The authors concluded that octahedral galenas formed at higher temperatures and that lower temperatures resulted in m ...
  Topic: Just how fast can the crystals we love and collect grow?!
alfredo

Replies: 5
Views: 672

PostForum: Minerals and Mineralogy   Posted: Oct 05, 2021 05:31   Subject: Re: Just how fast can the crystals we love and collect grow?!
Apart from pegmatite environments, I've personally seen specimens (miniatures to cabinet size) of other things growing in less than a month: Sulphur crystals in volcanic fumaroles. Gypsum crystals in ...
  Topic: Location in Romania
alfredo

Replies: 5
Views: 643

PostForum: What is it? - Where is it from?   Posted: Sep 30, 2021 16:58   Subject: Re: Location in Romania
Yes, Mathias, the "Siebenbürgen" on the label is the old German name for Transylvania.
  Topic: Question about an old specimen
alfredo

Replies: 8
Views: 742

PostForum: What is it? - Where is it from?   Posted: Sep 27, 2021 11:17   Subject: Re: Question about an old specimen
"Dognecea it was in Hungary but currently is Romania"

Some parts of Hungary are now in Slovakia and Serbia. One Hungarian mineral collector likes to say, "Hungary is the only country ...
  Topic: Will Barite save the world?
alfredo

Replies: 15
Views: 1203

PostForum: Off-Topic and Introductions   Posted: Sep 23, 2021 16:33   Subject: Re: Will Barite save the world?
That can only happen if the inside is hotter than the outside, then it can radiate more than it absorbs, so, if it is 40 degrees outside, the paint can't cool your home to below 40 degrees, otherwise, ...
  Topic: Sold as “Green stilbite”
alfredo

Replies: 11
Views: 1250

PostForum: FOR BEGINNERS: What is it? Where is it from?   Posted: Sep 17, 2021 07:46   Subject: Re: Sold as “Green stilbite”
Certainly looks like heulandite crystals colored by inclusions of celadonite, and almost certainly from a basalt rock rather than a metamorphic rock, but whether it's from Iceland or India or elsewher ...
  Topic: Online catalog of the minerals of the IGME collections - Madrid Community
alfredo

Replies: 4
Views: 17991

PostForum: IGME (Instituto Geológico y Minero de España)   Posted: Sep 14, 2021 13:05   Subject: Re: Online catalog of the minerals of the IGME collections - Madrid Community
We went last week to Madrid and visited the Geominero Museum, right next door to the IGME (Instituto Geologico y Minero de España). Curator Ramon Jimenez very kindly met us and gave us an introduction ...
  Topic: Announcing the opening of the New Gem and Mineral Museum of the University of Arizona
alfredo

Replies: 5
Views: 762

PostForum: University Arizona Tucson Mineral Museum   Posted: Sep 07, 2021 14:44   Subject: Re: Announcing the opening of the New Gem and Mineral Museum of the University of Arizona
One small warning: The museum is open, but so far only at rather strange hours for a museum, Monday to Friday, 10:00 to 2:00. No evenings or weekends. So don't drive to Tucson for the weekend to see i ...
  Topic: Mineral questions from a woodworker!
alfredo

Replies: 3
Views: 635

PostForum: Off-Topic and Introductions   Posted: Sep 04, 2021 23:28   Subject: Re: Mineral questions from a woodworker!
Welcome to the Forum, Ron. What are you using for crushing the minerals, and what size particles do you want to end up with? That will have some influence on which minerals might be suitable.
  Topic: Crystal Habit of this Pyrite Mineral
alfredo

Replies: 7
Views: 872

PostForum: FOR BEGINNERS: What is it? Where is it from?   Posted: Aug 05, 2021 12:41   Subject: Re: Crystal Habit of this Pyrite Mineral
In that case no pyrrhotite, and probably indeed pyrite as you thought, and perhaps also including other sulphides as Pete said.
  Topic: Crystal Habit of this Pyrite Mineral
alfredo

Replies: 7
Views: 872

PostForum: FOR BEGINNERS: What is it? Where is it from?   Posted: Aug 05, 2021 12:25   Subject: Re: Crystal Habit of this Pyrite Mineral
Also, check it with a magnet to see whether it's really pyrite, or might be pyrrhotite.
  Topic: About a rutile epitaxy on hematite in quartz
alfredo

Replies: 3
Views: 890

PostForum: Micros & Macros - Images of Minerals   Posted: Jul 29, 2021 21:35   Subject: Re: About a rutile epitaxy on hematite in quartz
Roger, I often saw such fractures in heavily included quartz crystals, and I wondered whether they could perhaps be caused by strain due to differential thermal expansion between the quartz and the ru ...
  Topic: Linarite or azurite
alfredo

Replies: 5
Views: 1451

PostForum: Conserving, Preparing and Cleaning Minerals   Posted: Jul 10, 2021 00:50   Subject: Re: Linarite or azurite
20% acetic acid makes azurite give off bubbles of carbon dioxide, although slowly, not fast like the effervescence under strong HCl. Linarite won't bubble in acetic acid of any strength.
  Topic: What is it?
alfredo

Replies: 4
Views: 969

PostForum: FOR BEGINNERS: What is it? Where is it from?   Posted: Jul 02, 2021 23:28   Subject: Re: What is it?
On the positive side, the outer rind on yours looks natural. Most of the ones that come to market from Brazil are painted green on the outside and have cement in cracks, etc. So I'll give yours some e ...
  Topic: Help with historical stone mystery - slag, or something else?
alfredo

Replies: 11
Views: 1465

PostForum: What is it? - Where is it from?   Posted: Jun 26, 2021 02:23   Subject: Re: Help with historical stone mystery - slag, or something else?
Given the direction of the Gulf Stream, I think pumice is more likely to reach Scotland from the Azores than from Iceland, and the Azores certainly have more silicic pumice-producing eruptions than Ic ...
  Topic: Help with historical stone mystery - slag, or something else?
alfredo

Replies: 11
Views: 1465

PostForum: What is it? - Where is it from?   Posted: Jun 25, 2021 14:01   Subject: Re: Help with historical stone mystery - slag, or something else?
Keep in mind that great pumice "rafts", sometimes several square km in extent, have been washed up on shores in Japan, Fiji and elsewhere that came from undersea eruptions and did not corres ...
  Topic: What kind of mineral is it ?
alfredo

Replies: 4
Views: 811

PostForum: What is it? - Where is it from?   Posted: Jun 23, 2021 10:10   Subject: Re: What kind of mineral is it ?
Reddit is obviously not the right venue to ask for mineral identifications. ;))

This stone is obviously some type of chert or jasper. No reason to think there is any arsenic in it,
  Topic: Unknown mineral from Pikes Peak pegmatite
alfredo

Replies: 23
Views: 3335

PostForum: What is it? - Where is it from?   Posted: Jun 13, 2021 20:49   Subject: Re: Unknown mineral from Pikes Peak pegmatite
"there is a single fairly planar crack that appears to be perpendicular to the long axis that shows up when the light hits it just right." ...sounds like an incipient basal cleavage? That, a ...
  Topic: Unknown mineral from Pikes Peak pegmatite
alfredo

Replies: 23
Views: 3335

PostForum: What is it? - Where is it from?   Posted: Jun 13, 2021 18:06   Subject: Re: Unknown mineral from Pikes Peak pegmatite
Have you tried fluorescence under UV? Danburite is often (unfortunately not always) fluorescent blue under shortwave UV. I know nothing about the fluorescence of euclase, but fluorescent response migh ...
 
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