Allophane

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This article is a place holder and needs someone to take it in hand and finish the first draft. If you would like to take this article in hand, leave a reply message below or contact Rock Currier via private message by clicking on the PM button next to my name at the top of the article.



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Can you help make this a better article? What good localities have we missed? Can you supply pictures of better specimens than those we show here? Can you give us more and better information about the specimens from these localities? Can you supply better geological or historical information on these localities?

Below are some preliminary notes I have made about Allophane. This entry and thread has been made as a place holder for information that you will hopefully contribute about Allophane. It should be in no way be thought of as a claim I have staked out to write about this mineral, and in fact is an invitation for someone to step forward and create the article about this mineral. If you are so inclined and have questions about the format that such an article should have, go the The welcome topic at the top of the Best Minerals forum and read what has been posted there. Also take a look at some of the more mature articles that have already been written like Rhodochrosite, Adamite, Millerite etc. You will need also to pick out other images of Allopane that will go into the article.


Allophane
Al₂SiO₅ H₂O Amorphous

Here will go general comments about Allophane

Allophane Rare species collections.
Al,Si,H2O
One of the clay minerals. Many localities have this amorphous hydrous aluminum silicate which is a weathering product of silicate rocks. It does not occur in crystals but the best specimens occur as colloform crusts resembling hyalite opal, and stalactitic masses. It also is found as powdery aggregates. Think of it as a specialized kind of mostly white dirt. Asked Dick Thomssen, an advanced micromounter with over 10,000 specimens in his collection and 40 years of experience, if he knew of any localities that produced micro crystals of allophane. His eloquent and wordy reply is as follows. “No.”

Allophane
England
Devonshire, Bridestone, Wheal Hamblyn. Crystalline allophane is reported at Wheal Hamblyn but that does not mean that it is found in nice euhedral crystals.

Allophane
New Zealand
Mt. Te Aroha, Tui Mine, Ruakaka Vein. On level two of this mine, 110km SE of Auckland, “Large pale blue waxy masses” of allophane are found.
1. Mineralogical Record, Vol. 6, 1975, p 29.


Allophane
USA
New Mexico, Socorro Co. Magdalena District, Juanita Mine




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Rock Currier
Crystals not pistols.



Edited 3 time(s). Last edit at 12/25/2012 11:31PM by Rock Currier.

Rock,

I just loaded a photo of a nice allophane from the Juanita Mine, Magdalena District, New Mexico. My dad and I have collected on the mine dumps there for the last 20 years, and while I have never seen euhedral crystals from the area, it does form in very pretty bright blue botryoidal masses. I can get a better quality photo of the specimen, if need be.

Philip

Allophone is amorphous so by definition will not occur in crystals except as pseudomorphs, which I am not aware of, but is possible. Many "allophanes" are found to be poorly crystalline kaolinite when tested, while others grade into evansite and other poorly crystalline minerals. The blue ones are apparently copper bearing.

Regards,
Ralph



Edited 1 time(s). Last edit at 03/26/2012 09:54PM by Ralph Bottrill.

Ralph,

Thanks for the information. If I would have looked at the allophane page, I would have noticed that the mineral is amorphous, not crystalline . From previous knowledge and the information I've read on allophane, kaolinite, evansite... my best guess is that the mineral is allophane. There are also several respected New Mexico mineral books (Northrup's book included) that list allophane from the district.

Thanks,
Philip

Philip,
We will take a better photo when you get around to it, but the one you supplied is good enough for the article. I put it in although we need someone to work on this article. Right now it is just a place holder waiting for someone to take it in hand and work on it.

Rock Currier
Crystals not pistols.