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Improving Mindat.orgSpecimen is not Lansfordite

1st Sep 2014 16:37 UTCMark Heintzelman 🌟 Expert

The image http://www.mindat.org/photo-628577.html has been listed under Lansfordite, but there is no remaining Lansfordite from this locality, it has all pseudomorphed to Nesquehonite. Further, this example is also a fairly poor representation for the original crystal structure described for Lansfordite, which would be much better represented by these rarer samples such as the following:

"Part of the translucent white material was in the form of small stalactites which in some cases showed crystal faces near the terminations. The whitish mineral proved to be quite soft and it had a striking waxy appearance, resembling melted wax. < . . .> June of 1888 Keeley returned to the mine and pried off nearly every scrap of Lansfordite left. The result amounted to about fifty small specimens, weighing altogether no more that half a pound. But the mineral had changed greatly in appearance. Where it had been translucent before, it was now partly chalky white and opaque. And at the base of the stalactites, where they had been attached to the overlying carbonaceous shale, radiating clusters had formed of small transparent crystals of prismatic habit. Here was a second mineral, apparently newly created by alteration of the landsfordite." <...> Genth and the crystallographer, Samuel A. Penfield of Yale, later published the results of their chemical and crystallographic tudy of the second lot of material (AM. Jour. Sci (3), 1890, 121-137). Some months after Keeley collected these specimens, alteration proceeded still further to the opaque and chalky-white substance. All of the original lansfordite had now changed to another mineral, nesequehonite."

(A. Montgomery: Mineralogy of Pennsylvania, 1922-1965, part 4, 64-65)

MRH

PS: if the managers feel there NEED be a representative image for Lansfordite from this locality, I will attempt to take and provide a better image of this particular specimen.

1st Sep 2014 19:00 UTCKnut Edvard Larsen 🌟 Manager

Message sent.

1st Sep 2014 20:08 UTCMark Heintzelman 🌟 Expert

Second note:

All of the specimens currently posted only to the Nequehoning locality really should be moved to the Nesquehoning Coal Mine locality. There was only one locality and one find for these specimens, the #1 tunnel at the Nesquehoning Coal Mine.

MRH

3rd Sep 2014 05:08 UTCBrian Kosnar 🌟 Expert

Hi Guys,

Thanks for the note. I'm removing Lansfordite from the photo caption. Please let me know if I should make any other changes. I'm not an expert on Nesquehoning minerals, and I simply copied the label information from Allen Heyl's collection.

-Brian

3rd Sep 2014 14:44 UTCReiner Mielke Expert

I would say the specimen is even questionable as to whether it was even Lansfordite to begin with. Like Mark pointed out, it does not match the description for the species. I think it needs to be tested before even being posted as an example of nesequehonite ( pseudo Lansfordite).

11th Sep 2014 22:41 UTCMark Heintzelman 🌟 Expert

Brian fixed the first image, but the sister image was not corrected and is still labeled Lansfordite, and still shows up under Lansordite in the detailed mineral report.

Can a manager just do a quick fix on this? We are all in agreement that it need be done.

Thanks,

MRH

11th Sep 2014 23:43 UTCRob Woodside 🌟 Manager

Done. Thanks everyone.

edit: What about Reiner's point that this doesn't look like Mark's piece or the description? Mark please upload a picture of your specimen.

12th Sep 2014 01:57 UTCMark Heintzelman 🌟 Expert

Thanks Rob,

Considering the appearance and the minute size of this specimen, I wouldn't actually doubt it's identity. It does look like a compacted crystalline cleavage of Nesquehonite, but most likely of primary Nesquehonite, the noted crystallization formed during the alteration of Lanfordite, and not actually a pseudomorph of Lansfordite. It is certainly not visually representative of Lansfordite in any way. (you can see some prismatic crystals of primary Nesquehonite at the base of the specimen I've posted above).

I will try to take a better image of my pseudo specimen and add to the database. (I'm actually way behind on photography, but I'll make a special effort for this one).

MRH

12th Sep 2014 16:51 UTCRob Woodside 🌟 Manager

Thanks Mark

9th Oct 2014 01:42 UTCMark Heintzelman 🌟 Expert

Sorry it took so long, but a new and far better image of this specimen has been added to the database. http://www.mindat.org/photo-640068.html

Although not Lansfordite anymore, it is the best example we have of the appearance of an actual Lansfordite crystaline stalacitie from this locale.

Despite all efforts made, every Lansfordite specimen from this locale had altered to Nesquehonite.

MRH

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