FMF - Friends of Minerals Forum, discussion and message board

[Jordi Fabre]

Associated with this topic: https://www.mineral-forum.com/message-board/viewtopic.php?t=658, and maybe almost more interesting, is the sensitivity of many minerals to the sunlight and the lack of awareness from many collectors to this fact.
Gail proceed carefully protecting their minerals as far as possible of the sunlight, but this is not so common, many collectors don't do it and this can create frustrations later.

It's a long list of minerals that after being millions of years in the interior of geodes with 0 light and being continuously exposed to sunlight, suffer color changes or them decay. Some of them such as Vanadinite, for example, are not too much known...

We discussed a little bit here about it on the past: https://www.mineral-forum.com/message-board/viewtopic.php?t=361, but is never enough to warn everybody about it.

Someone have a list (or know if / where this list exist) of minerals sensitive to sunlight or that decay with it?

Jordi

[Tobi]

I never had personal experience with the fading of mineral colours, but my displays are in a room where no direct sunlight can reach them, that maybe a reason why i never had this problems ...

I found a small list of light sensitive minerals in a book by Walter Schumann (famous German professor of geology and book author), and he lists:

Amethyst
Apatite
Argentite
Bromargyrite
Chlorargyrite
Cinnabar
Citrine
Crocoite
Fluorite
Hiddenite
Kunzite
Miargyrite
Morion
Orpiment
Proustite
Pyrargyrite
Realgar
Rose Quartz
Stephanite
Topaz
Vivianite

[Jordi Fabre]

Fine! everybody could add species to this list and when we don't get more messages, I will arrange a new list with all species suggested.

On the meantime let me add to the list Silver and Vanadinite.

Jordi

[Vasco Trancoso]

Hi Jordi

Don´t forget Inesite

Thanks

Vasco

[Peter Megaw]

Interesting that most all varieties of colored quartz are light sensitive

Here are some others

Calcite (there are yellow ones from Santa Eulalia that turn pinkish on 15-20 minutes exposure to sunlilght. If you put them back into the dark they return to yellow in 10-12 hours...and you can repeat the process..I did it 3 times before I got bored and stopped. However, on 30 minutes to an hour's exposure they turn white and stay that way)

Creedite purple creedites are VERY light sensitive.

Native Mercury...will evaporate

Wulfenite: Red Cloud wulfenites will fade over time

[Matt_Zukowski]

Tobias listed apatite as light sensitive. What about the beautiful green gemmy xtals from Sapo. I have one sitting on my shelf in the office.

I think this topic is more complicated than to come up with a list of light sensitive minerals. To be useful, a list of light sensitive varieties and localities, organized by mineral, should be developed. A number of entries into the topaz section were motivated by Gail's initial post.

In fact, this topic brings up an idea I have had about starting a wiki for information on handling, cleaning, and preserving mineral specimens. Much good information is spread throughout forums and other sources on this and other websites. But it can be difficult to find the info, and you don't know if the info is accurate.

I don't know anything about how to make a wiki, but i know what they can do (wikipedia), and i would be happy to devote some time to making this work. It seems what is needed is for a bunch of people interested in this topic to agree on a common nexus for for this info. Perhaps the best thing is to attach it to this website or mindat, places where many already go to find good info (wikis seem to need a critical mass of people to get it going, once the info gets extensive then more and more people will join the effort). Wikis can be edited by anyone, but there are also higher levels of editors who can flag suspect info, reverse bad edits, and even lock topics where people put specious or bad info. There seems to be much free wiki software.

What do people think?

[Jordi Fabre]

[Matt_Zukowski]

Jordi - While I would be happy to help in any way that is acceptable to the group, cutting and pasting a bunch of forum threads into a distinct area in this website might not be as useful. I don't know if i am trying to bite off more than i or anyone else wants to chew, or if mindat has already considered and discarded this notion.

One of the things that makes mindat so useful is that it is a bunch of info organized into a standard format. Once a reader knows how the organization is setup, they can quickly navigate the site to find more information. Mindat is a wiki in that multiple users have various levels of authority to edit information. Unlike most wiki's however, mindat does not allow most users to make most edits.

Perhaps the idea i put forth may work best in conjunction with mindat. They are already organizing information by mineral, and it may be simple for them to add a section under each mineral for handling, cleaning, and preserving information. This may mean it would be a lot less work to implement this under mindat than FMF. Do people think this is a good idea? If so, does anyone here know anyone over at mindat i could talk to about this?

[Jordi Fabre]

Maybe some kind of relationship between FMF and Mindat? I can try it (although I ignore if they would be interested for it)

What opine the other members of FMF about this possibility?

Jordi

[Gail]

I am very close and good friends with Jolyon, and know most of the managers. I think it would be a nice collaboration. They are always interested in furthering information.

[Matt_Zukowski]

Please let me know what i can do. If I can get an introduction to Jolyon, I'd be happy to explain in more detail to him what i am thinking and offer any help i can.

[Gail]

I would love to introduce you, you are on mindat already right? Please PM me on the message board on Mindat and I will get your email address and introduce you to Jolyon and help explain your thoughts and desire to do this project with he and his managers.
Thanks!

[Jordi Fabre]

[keldjarn]

This topic was discussed in the Mindat Forum for Mineral cleaning and preparation in a thread started on nov. 6th 2008. A list of light sensitive minerals was discussed. As mentioned by others both light at different wavelenghths and the heat generated by light may deteriorate and fade mineral specimens - and other objects. Thus there is also a specialized area of preservation and display of museal objects that focus on different lighting that will reduce the fading provoked by light. There are many articles to be found on the internet and comsultants and companies that specialize in such services to museums.
From a theoretical point of view light has a potential of deteriorating or fading minerals by different mechanisms and sensitive minerals might be grouped accordingly i.e.:

1. Light inducing photochemical reactions as is the case with silver-bearing minerals turinng black on exposure to light when in an atmosphere with oxygen and sulphur, the changing of realgar to orpiment etc.

2. Light inducing permanent colour change in typically "smoky" and "sherry" coloured minerals by restoring an internal structure that has been damaged by background radiation from the rocks where the minerals were formed. Such changes will happen more rapidly to sherry and smoky coloured topazes than i.e. to smoky quarz. (The colour may be temporaryly "restored" by irradiating the crystals artificially.)

3. Light inducing changes to the orbits of the electrons in the chromophores that are responsible for different colours in minerals. Many desireable mineral specimens and crystals are coloured by the presence of such foreign compounds - the pure mineral itself being colourless. In some cases these changes may be reversible i.e. as for the Hackmannite variety of Sodalite containing a sulphite ( SO3-group) belived to be resonsible for the colour change.

In some cases more than one mechanism may be present.
While light-sensitive minerals falling in group 1 and 2 may be considered to be susceptible to light regardless og the locality, minerals in group 3 may have different properties depending on the locality because the chemcial and structural basis for the colour may differ depending on the environment in which the mineral crystallized.

Knut

[Jordi Fabre]

Fine, the comments of Knut shows very well the facility to use here the Mindat's discussions and maybe there our discussions. If already discussed in Mindat, easier to complete the list with his discussion and then communicate our results to the Mindat's thread, or something like this?...

BTW, Knut could you please publish here the link to that Mindat's thread? All links to Mindat are permitted here, you can write it directly.

Jordi

[keldjarn]

https://www.mindat.org/forum.php?read,5,115692,116087#msg-116087

[David Von Bargen]

I think that this is a good idea and it can be implemented fairly easily. I would suggest that it be extended to some other best practices for displaying and storing specimens that might have other problems than light sensitivity (for instance deliquescence or dehydration, pyrite disease, heat sensitivity or evaporation). This field would need to be added both on the mineral level (ie for silver halides where it effects all specimens) and on a location level for the species (or a color variation). One problem I see is when you have a mineral that is found in several loctaions in an area (ie the sherry topaz from a number of localities on Topaz Mountain, Utah). These locality specific problems should probably be indicated on the mineral page (maybe just by links to the specific locality page).

There should also probably be an article written about the subject that would include some more general information (like heat sensitivity of heavily included specimens). While there does have to be a "lead" editor for this, they can designate other people to edit and add to this information.

[Jordi Fabre]

Sound as a deal ;-)

Matt, as David is one of the editors of Mindat (I beleive), do you want to be the "lead" editor requested from David? If yes, do you wish work here in FMF with us and then, when the final list be ready, communicate it to David to be implemented in Mindat? Otherwise, you should do it in Mindat, or maybe in both sides?...

What do you think David?

Jordi

[David Von Bargen]

Yes, I am one of the "managers" and also do some programming on mindat. The way I envision the article is as a general introduction to the subject of storage and some more general things to do and not do (thermal shocking minerals, don't store acicular minerals in cotton, etc.)

We can add fields to the minerals for storage conditions for a mineral (ie light sensitivity for silver compounds). Also will add a field for the mineral/location pair that generates the mineral lists at localities for any special problems of the mineral from that location. The mineral list one can be edited by anyone who has an activated membership. The mineral pages are normally only editable by managers, but we can give certain people "helper" status to edit mineral pages for projects such as this.

[Matt_Zukowski]

David - you sound like you have the general idea fleshed out pretty well. By allowing the general user to post info on the locality/mineral pages, data can be wiki'ed together more quickly for a particular species, and then someone with higher rights can vet and summarize that data on the main mineral page.

Is there something i can do more specifically? I could collate and edit an article if people want to feed me snippets from various sources. I could also begin populating the field on the mineral/location pair with what little I know, when the field becomes available. Might I also suggest an announcement on the homepage inviting others to add their info. Please let me know.