FMF - Friends of Minerals Forum, discussion and message board

[Jean Sendero]

Hello again,

Here is a question about the provenance of the mottramite from Mapimi that came out during the Tucson show this year and was available through a handful of dealers. Still, not often seen on the market. Despite what some people are saying, I find them absolute smokers and every Mapimi collector should have at least one in their collection.

The mottramite is labeled as coming from Level 35. I never questioned this although according to the map published in the Min Rec (vol 34, No 5, p 31) and reproduced in this forum ( https://www.mineral-forum.com/message-board/viewtopic.php?p=8708#8708 ), we seem to be running out of levels where secondary minerals can occur. Basically, the section suggests that Piso 15 (Level 8) is as deep as it gets for secondary minerals. So, how far down is level 35?

Over the weekend, I was fortunate enough to look at more or less 50-60 specimens of the mottramite. On a couple of them, on the back side of the specimen, I was able to see some pyramidal pointy yellow wulfenite crystals to 0.5 cm in length in a limonitc matrix, without green mimetite. These are very similar, if not the same than the wulfenite that started to come out in 2009 and labelled as lugar San Juan Poniente nivel 6. I will try to add photos later.

My questions,
1) Can someone tell me where is level 35 in reference to the published section?
2) Or did the miners made up an area in order to not divulge the real provenance?
3) Is it possible that the mottramite was found while digging for wulfenite and the miners broke into the mottramite pocket?
4) Can the real provenance be the San Juan Poniente?

Cheers

Jean

[Peter Megaw]

Jean, I have also noticed the yellow dipyramidal wulfenites on the matrix of several of these mottramites and was also struck by how similar they look to the San Juan Poniente wulfenites. I believe that is where they came from and how I will label them.

It is entirely likely that they followed the wulfenite zone into mottramite. At the Total Wreck Mine in Arizona, wulfenite gives way vertically to mottramite and there are even pseudomorphs of mottramite after wulfenite found there.

As far as I know even with the original level nomenclature the mine did not get anywhere near a Level 35.

(NOTE: These have been analyzed by several competent mineralogists and they are indeed mottramite...some were sold early on as arsenian descloizite)

[Jean Sendero]

Thanks Peter,

you confirmed my suspicions and I will likely label them as well as San Juan Poniente. The wulfenite is really the key association. Too often the mottramite specimens have been cleaned so much that the soft limonitic matrix at the back has been completely removed.

Any thoughts on the vanadinite post?

Cheers

Jean

[Jordi Fabre]

In my opinion it could be from San Juan Poniente the same as it could be from any other place, the Wulfenite is dipyramidal like the Wulfenites from San Juan Poniente, yes, but also they are more yellowish, corroded, and they haven't Mimetite.

The miners tend to say lies, but after Tucson Show I got several different messages from the people who said to be the discoverers of the pocket. They corrected to me the find's date (not 01/2012 but 11/2011) and they all said the same: level 35. I know is not a real proof and probably "level 35" it doesn't match the real distribution of the mine, but maybe matches some kind of informal distribution that the miners use. The guys who contacted me were very coherent and they gave to me many other details including the names of the guys who participate in the discovery.

Anyway, is a classic that all miners protect the real places of new finds, so hard to say what the truth is…

[Jean Sendero]

I have attached a couple of photos of a mottramite specimen with the wulfenite on the back side. I am not an expert at taking photographs but the color and form of the wulfenite are bright yellow without "corrosion". I thought the corroded ones are from the Santo Domingo area and are more blocky than pointy.

[Jordi Fabre]

Some Wulfenite from this find looks corroded Jean, not yours, and the color is more yellowish than orange as your specimen shows.

Again, who knows... ;-)

[Jordi Fabre]

[Jean Sendero]

Jordi,

This is why I brought up the wulfenite. We are never sure but I am trying to improve it by looking at the associated minerals, matrix, etc......

Yesterday, I gave a good clean and trimming to the specimen above. Additional surprises came up. A large part of the matrix is actually made of massive white quartz and to top it up, I found two well formed crystals that are coated with mottramite. I will post photos later this week. I have not seen a lot of quartz from Mapimi but have some members seen some quartz associated with some wulfenite specimens from San Juan Poniente specimens?

Cheers

Jean

[Jordi Fabre]

Jean,

Are you sure is Quartz? in some of my specimens the white material is Baryte...

[Jean Sendero]

Oh yes, very hard, glassy, no cleavage, etc....Wait for the photos. I have to go to work but when I get back this evening I will post them.

Jean

[Jean Sendero]

Jordi,

a few quick pics. The matrix or under lying material is quartz for sure. I had to stop using the trimmer, some of the mottramite stalactites broke off at the first pop. The crystals covered by mottramite have a quartz base but the crystal terminations and shapes are not typical of quartz (see two pics below of two different specimens extracted from the original above).

Can it be a Baryte? Maybe but but I have never seen this crystal shape for Mapimi Baryte.

Has the quartz replaced Baryte? The glassy and massive appearance of the quartz makes me believe that it is not a pseudomorph of quartz after Baryte coated by mottramite.

I would greatly appreciate your opinion.

Cheers

jean

[Jordi Fabre]

Please check if this white material scratch the glass. Thank you.

[Jean Sendero]

Jordi,

it does, and the sribber does not scratch it either. Very hard.

[Jordi Fabre]

Well at this point I can't tell you nothing else. The similar material that I have is Baryte but if yours is so hard then it should be Quartz.

If you have the chance please bring it to the InnSuites in Tucson 2013 and with the specimen on my hands maybe I can tell you something more.

[Jean Sendero]

The Baryte you see in your specimens is more of a platy tabular form, correct?

Cheers

Jean

[Jordi Fabre]

[GneissWare]

Jordi, Perhaps posting a photo of the specimen with Baryte would be helpful.