Magenta Red Tiger Unknown

This tiny magenta-red tabular crystal is on Diaboleite from the Mammoth St. Anthony Mine. The first photograph has a field of view of 0.5 mm. The second photograph shows a less magnified view, with associated leadhillite, as well as two other unknowns--one a pale yellow sphere and the other as pale green botryoidal. The field of view of the second photograph is 1.0 mm.

Bob

Hi!

Yedlinite?

Regards,
Franz

Bob,

GOOD FIND!

I'd label that a Yedlinite and stick it in my Tiger drawer until I could have it checked.

Did that one come as a freebie with a Diaboleite purchase?

Looks just like the Yedlinites I've seen around, same association.

Regards,
Michael



Edited 2 time(s). Last edit at 08/18/2008 09:43AM by Michael D. Cline.

Hello Bob,

I would be careful before I label it yedlinite. I have several specimens of diaboleite, and leadhillite with small red crystals associated with and on the diaboleite. The red crystals could be cuprite, iranite or even descloizite. The key to identifying the yedlinite is the crystal structure, color and associations. The crystal should be rhombehedral and the color is purple not red. The yedlinite that I have seen are associated with diaboleite, dioptase, wulfenite. fluorite, cerussite, and phosgenite. I personally have never seen yedlinite associated with leadhillite.

I hope this helps,
Brent

Brent, Michael, and Franz,

Thanks for your replies. I had to spend the evening on something else, but I will reply in full soon. I am attaching a photograph of another area of the piece. This mineral has a decided violet tint, but I am not convinced it is Yedlinite, only that it could be. The specimen itself, a large miniature, has very complex mineralogy with many other species present.

By the way, Brent and Michael, you have seen many specimens of Yedlinite? You are very fortunate. I will trade you for something you'll really like for one. "Excuse me Mister, do you have any spare Yedlinite?"

Cheers,
Bob

Hello Bob,

I have had the opportunity to inspect six yedlinites closely under a microscope. The matrix and associations are always the same. From what I understand, Neil Yedlin found the material in some old specimens being sold as wulfenite. There were perhaps four pieces that had the then unknown violet crystals on them. All the yedlinites that I know of come from these specimens. Also, all the yedlinites were mounted in micromount boxes and labelled as either yedlinite or violet unknown. I am not saying that there could be more yedlinite out there that has not yet been discovered, I am just repeating the history for the known yedlinites.

I wish that I had one to trade, but I am afraid that I have only one.

Brent

Brent,

The idea of a spare yedlinite is a joke, they are so scarce. Of course, should you come across one, let me know.

The association that you mention is very rare. From the purchase of my first Mammoth Saint Anthony Mine specimen in about 1978, (a matlockite, with superb diaboleite, wherryite, and many still unidentified species), I have been actively pursuing specimens from there. Now, out of perhaps Tiger 300 specimens now residing in my collection, including quite a number of specimens with diaboleite present, I don't think I have one piece with both diaboleite and wulfenite on the same piece.

I spotted the cranberry-red crystal that was depicted in the message above a few years ago, on a specimen I have had for 14 years now. Even at the highest magnification available to me with my stereoscopic microscope, (120x), I could not make out much detail concerning the crystal, although it's rich cranberry red color was very evident against the deep blue diaboleite. My new photomicrography set-up allows for greater magnification, albeit with less convenience than simply putting the piece under the microscope. All of the images are composites of up to 15 layers, put together with CombineZP. My photography set up is still less stable than it eventually will be, which, when I can add stability, should add to my ability to resolve the features of tiny crystals.

Cranberry-red download 7.jpg shows an unusually developed offset triangular group of crystals on diaboleite. The color of the pale blue diaboleite towards bottom center is accurately depicted. The flattened colorless crystals in the upper center are possibly matlockite or leadhillite. The field of view is 0.5mm; a composite of 11 images.

The specimen itself is ostensibly a leadhillite specimen, but like best Mammoth-St Anthony material from the anomalous zone, the mineralogy of the piece is intricate and fascinating, and I have spent hours examining it and trying to fathom its mysteries under the microscope. It is a large miniature, at one time in the collection of John L. Parnau. Mr. Parnau had written a note saying "Yedlinite?", which did not accompany the piece, but was related to me. The piece possesses exquisite crystals of blue leadhillite, pale yellow leadhillite, and colorless leadhillite. Also present are very interesting pyramidal hemimorphic crystals of diaboleite, the longest over one cm in length. Other species present on the piece are caledonite, phosgenite, quartz, and a number of unidentified species.

Interestingly, despite having spent long hours examining this specimen under the microscope, I spotted three or four additional crystals of the cranberry-colored unknown over the past couple of days that I never before had spotted. With Tiger minerals, one can spot new things and continue to learn more about the deposit's paragenesis each time one examines certain pieces. I now have enough grains for an analysis, which I will undertake to do sometime in the future.

As to a guess of what these crystals could be, other than yedlinite or something new to Tiger, I am drawing a blank. I have never seen descloizite that is even close to this almost electric cranberry red color. The Mammoth St Anthony Mine iranite I have seen, and that in my collection from Tiger, are bright orange-red, unlike this material. I don't believe these are cuprite, either. Although the paragenesis you describe exactly matches the publication data, I was reading in the Mineralogical Record (Neil Yedlin's memorial in 1979, Volume 10, number 4, by Ron Bentley, et, al.) that Yedlin's working name for the species was "cranberryite" and Bentley described the piece Yedlin showed him as "a very, very minute cranberry-red crystal." Somewhere, also, I heard that Yedlin found the pieces while perusing though diaboleite specimens in Schortmanns Minerals' back stock, although that is unsubstantiated. My question is whether the species might occur in some other paragenesis. Time will tell. Regardless of what it is, the results will be fascinating.

Bob

Hello Bob,

The material that your unknown is on sounds a lot like the material that the pinalite was found on. The pinalite matrix is primarily quartz with diaboleite, "chromium leadhillite", leadhillite, matlockite, phosgenite, murdochite, anglesite, caledonite, cerussite, connellite, wherryite, iranite, small yellow wulfenite and unknown red crystals that I at first called iranite. After discussion with some authorities on Tiger material, I now think the crystals are cuprite. Attached is a photo of one of the crystals on quartz.

Brent

The Yedlinites that I have seen in person are a beautiful, relatively pale, lilac. The photos posted here tend to portray it as a bit redder and darker than what I have seen. I certainly don't know just how dark and red it can get, but there are so few legitimate specimens of this ultra-rare species, that it is unlikely that its appearance varies much from what is portrayed on Mindat with 4 photos.

According to the yedlinite descriptive paper, Neal noticed the material on specimens obtained from Schortmannn's and deposited several fragments at the NMNH in Washington. Other specimens were noted in the museum's collection. The color is described as red-violet and is slightly dichroic.

For me it looks like litharge
Marius

I had read the descriptive paper for Yedlinite and Yedlin's discovery is right there in the introduction. I am not sure how I missed that.

The specimen that has these tiny cranberry red crystals does not have the same association as the Pinalite. It sounds similar, but it is not the same. This piece actually is lacking in any matrix, but is completely mineralized, mostly composed of blue leadhillite and diaboleite.

In contrast, my first Tiger specimen, which I mentioned in the beginning of my post prior to this one, does agree closely with paragenesis reported for Pinalite. The matrix of this specimen is a pale tan vuggy fine grained quartz. Associates on the piece include superb diaboleite, transparent green wherryite, matlockite, and yellow "chromian" leadhillite. The linked photographs and the attached photographs are all from this piece. Just for curiosity, I ran an analysis on one of the yellow leadhillite crystals. Indeed, they are leadhillite, but there was no chromium present. I don't know of another analysis of this pale yellow leadhillite, but its reported status as chromian is widespread. There is also cerussite, as twinned and reticulated crystals, and hematite, as tiny red cleavages, present. In addition, this specimen has numerous unidentified species, including rich amounts of a lead-zinc-copper silicate mineral in two distinct forms, possibly cuprian larsenite, and some acicular flexible yellow crystals that will be the subject of another post in this forum in the future.

I agree that Brent's red crystals look like the color of cuprite. The color seems right. Thus, perhaps two assumptions made in the literature are potentially incorrect, the "iranite" reported to be associated with pinalite might be cuprite, and the "chromian" leadhillite with no chromium.

Bob

I think the pale leadhillite is cerussite and the smal red x is litharge and the yellow is massicot.
I have seen this combination of minerals often in the Laurion slags
Marius

Marius,
Yes, you could be right, although the color of the red mineral has a blue tinge that I would not expect to see in Litharge and some of the crystals actually appear purple. By the pale leadhillite, do you mean in the last photograph with the red unknown, Cranberry-red download 7.jpg? If so, then I agree it could be cerussite. I don't plan to have that one analyzed, but I will analyze the red stuff. Thanks for your input.
Bob

Hello Bob,

I am of the opinion that iranite does occur with pinalite. I have attached a photograph of orange crystals associated with pinalite. These have not been analyzed but they are quite differrent than the wulfenite that is found on this matrix, (second photo attached).

Brent

I have been told that there is a specimen in the Smithsonian that is lousy with Yedlanite crystals. More than 100 xls on one specimen.
Rock

Rock Currier
Crystals not pistols.

Hi Bob: Just found this discussion otherwise I would have responded sooner! As you and others may know (Hi Brent), my intense interest in Tiger mineralogy has been driven over the years in my search to find an "undocumented" Yedlinite among several of the other extremely rare species (Pinailite, Bideauxite, etc). First regarding your possible Yedlinite, I have in my collection a similar unknown specie, cranberry-red, rhombohedral, sitting on a Diaboleite crystal. It too is so tiny (@ 100X) that repeated attempts to get a better view or picture has failed. One problem I see is that when it is situated on Diaboleite, the blue color tends to mask the true color of the unknown possible Yedlinite. One criteria I believe that is important in indentification of Yedlinite (besides habit) is that the color has a distinct lilac tint. If you look at two of the Yedlinites I have posted on Mindat (Sugar White & Mike Kokinos), this lilac tint is quite evident. Of note here is that both of those examples were associated with Wulfenite. Now I always thought that one way to discover an "undocumented" Yedlinite was to find Diaboleite associated with Wulfenite which is very rare in itself. I discussed this topic with Dick Thomssen recently at the June NCMA conference. Dick's observation was that Yedlinite was found in two associations: the one with Wulfenite and another rich in Phosgenite, as clear separate crystals. The photo of Dick's Yedlinite I took some years ago (posted on Mindat) occurs with this second association, and is more cranberry-purpleish red, and by the way quite prismatic. While Dick and I never discussed if Leadhillite could be associated with it, my opinion is that Yedlinite probably does not occur with Leadhillite. FYI, see the Encyclopedia of Minerals first edition, photo page 128 for another Yedlinite example- that one to my eye is more cranberry red.

So what is it? Iranite, or something else - I am not sure? The pic of Dick Thomssen's Iranite I posted on Mindat definately has an orange color tint to the red and is actually quite bladed (and was embedded in yellowish Cerussite) . Now in a recent discovery (late last year) of a new Pinalite specimen (see my pic on Mindat), I found a reddish, prismatic crystal (see attached pic). Brent and I thought that it could be Iranite, but a later look at it by myself showed a wedge shaped termination that looked all the world like a Crocoite! Unfortunately, when I took the specimen to NCMA this year for others to look at, the crystal dislodged and fell off- this picture is the only evidence left. Of note also in the picture is an orange colored grouping which was too small for a visual ID.

So Bob, good luck and I hope you manage to get an ID on the unknown(s).

Bruce

Hi All,

Very interesting topic. I have a couple of things to add. I think recently there was a paper out somewhere about how "chromian cerussite" recorded from some localities often contains no chromium, perhaps this is relevant to the "chromian leadhillite" that here is recorded as containing no chromium. I've not read the paper - but it might point someone in the right direction!

I have seen two yedlinites and they seem to have a more lilac tinge to their colour IMHO. I will be able to study one of them again next week - so I will have a look at the paragenesis and see how it corresponds to everyones comments above.

Cheers,

Mike

Yes, this is an interesting topic. The minerals of the Mammoth St. Anthony Mine are my personal favorite, and any discussion relating to them is of keen interest.

Rock, I would like to see that Yedlinite specimen someday. You have got some incredible Mammoth St. Anthony Mine material yourself. I would like to hear the stories of the blue leadhillite and the pale green one that were in the American Mineral Treasures case.

Brent, the two crystals in your photographs warrant more attention. I have to say that iranite does not spring to mind when I looked at them, but who can tell what will happen upon analysis. The pale yellow crystal is similar in color to the stolzite I discovered on a Tiger piece. It would be interesting if the crystal also turned out to be stolzite. I am attaching a photo of what I think could be iranite, but from a different association--rich fornacite, some altered, associated with willemite crystals, some of which in the richest area of fornacite are orange, presumably chromian (there we go again Mike), in cellular smithsonite, with other associates. The abundance of chromium in this piece is what makes me thing this red-orange material could be iranite. Again, the associated wulfenite on this piece are orange and are tabular. This cluster is much different in color and in form.

Bruce, I am stunned by the loss of the one crystal. I would have liked to have taken a look at it myself. Perhaps another will turn up.

I looked again tonight at the Matlockite specimen I mentioned as being my first Tiger piece, and that the desire to understand what I was looking at spurred my interest in Tiger material. The day I purchased that specimen in about 1978, I announced to the dealer I purchased it from that I would specialize in minerals from Tiger. "Good luck," he told me, "The mine closed in 1953, and material is very scarce."

I wondered if there was any trace of wulfenite on the piece, and there are a couple of indistinct areas that could be wulfenite. I found another group of the lemon yellow elongated crystals tonight, in addition. Photo attached.

Best regards,
Bob Meyer

Hi Bob,

I am particularly familiar with the Merehead quarry locality in England rather than Tiger, but they share some intersting similarities - diaboleite, fornacite, wulfenite etc etc and other rarer lead oxychlorides. (see Turner 2007 in min mag.) I am often looking at Tiger specimens to help me work out what might be present or what I might expect at Merehead. Anyway all of this is to say that the lemon yellow prismatic elongate mineral you have there in your last picture looks very similar to mimetite that we find in association with cerussite, hydrocerussite and diaboleite at Merehead.

With these similarities in mind, I'll throw something else into the mix - the "magenta-red 5 download" picture looks similar to the colour and platy reflectivity that is indicative of parkinsonite from Merehead Quarry. parkinsonite is a molybdenum lead oxychloride, and considering the occurrence of wulfenite and other lead oxychlorides at Tiger, I would assume that it is a possibility - BUT The only problem is that parkinsonite clearly does not look similar to the other pictures of the red unknowns you have posted, would you say that number 5 is a fair representation of how the material looks (or does it look more blood red and reflective than the others as an artificat of the imaging process), could you have two red minerals here?

Cheers,

Mike



Edited 2 time(s). Last edit at 08/25/2008 11:45AM by Mike Rumsey.

Hi Bob, Bruce, Brent..&..whoever else is reading...

I was able to look at the two Yedlinites today that I have access too (British Museum collection), they came from Neal Yedlin and have been XRD verified so their identity is assured. Interestingly their colour in overcast daylight and my normal diffuse microscope light is grey with very faint lilac-purple undertones, they only appear more cranberry-red when viewed under very strong intensely focused light yet still retain a dominant purplish-lilac colour. They do not look like the pictures above. What is more intreguing is that the original label describes them as "the new cranberry-red mineral"...could it be that yedlinite fades over time, or undergoes somesort of photosensitivity reaction to darken it? I have noticed various degrees of photosensitivity in other lead oxychloride minerals, Mereheadite can dull and darken on exposure for example, but the effect does not always seem to happen.

These yedlinite specimens have been on display since the 1970's in full daylight so perhaps this is something to be aware of - perhaps someone already is - can anyone fill me in here?

My guesses on the association from a quick look, without knowning the mineralogy or habit common of Tiger minerals is: yedlinite occurs within cavities in an almost cellular matrix rich in, diaboleite, hundreds of tiny transparent prisms perhaps ?hemimorphite-like?, many green needles of dioptase/atacamite, fluorite, quartz xtls, and wulfenite.

I also had a quick look through some of the other Tiger diaboleite holdings here - to see if anyone previously had noticed these small red embedded crystals that started this topic... Unfortunately I did not find any of them but my magnification is only limited to x50.

However I did find two specimens from the 1940's that contain crystals identical in colour and form to the Neal Yedlin yedlinites that we have in the collection, one contains about 15 crystals, the other about 7. So Bruce, you might be able to tentatively add two more specimens to your global yedlinite tally! (that makes 4 in the Natural History Museum, London, (originally called the British Museum (Natural History dept.))

One of these 'new' specimens has a crystal that is fantastically perched upon the very top of a dioptase(?) crystal - gorgeous! - I'll see if I can get a picture done sometime. Also interesting to note is that the wulfenite present on these specimens is poor, infact on both of the newly discovered yedlinite specimens wulfenite is perhaps less common than yedlinite.

I hope this is of interest.

Cheers,

Mike

Bob, Mike, Brent, everyone.: Bob, regarding your post today, Joe Ruiz and I believe that your Iranite is indeed Iranite. Congratulations, Bob, the yellow unknown Joe and I looked at and we are positive that it is Pinalite- we have seen so much Pinalite lately; beside the color, the striations, the wedge shaped terminations and twining assists in its identification!

Mike, regarding Yedlinite, I believe that it also forms crystals that could be confused with cuprite. A an example, see this unpublished Yedlinite pic from the Mike Kikinos specimen I took last year-although it is slighly out of focus, the habit (trigonal) is evident-note the deep violet color. Will be interested in hearing more about the specimens in the British Museum. Cheers. Bruce

Mike,

It sounds like an enjoyable job, curating such a collection, and being able to care for such holdings. You are doing good work, too. The addition of two more known specimens of yedlinite is an important achievement. I would certainly love to see some photographs of these specimens, and I expect there are many others who would also appreciate seeing them.

Since we are enumerating known specimens of yedlinite, I was talking with collector Bob Boggs not long ago and he told me the story of an excellent specimen he saw in the Harvard University micro collection. He visited the collection some years ago for two days. On the first day, he noticed the yedlinite in one of the drawers. "It was beautiful, with many crystals," he said, and it was right in a drawer in an area where visiting collectors might be able to spend time without being constantly supervised. Bob had spent all day there and hardly saw a soul. Bob pointed out that this piece was valuable, and was surprised to see such a specimen out in the open in such an area. The next day, the curators had corrected that lapse, and put the specimen in a safe.

I also have a fondness for the minerals of the Merehead Quarry, or perhaps it is also fondness for that type of mineralogy. I do have one photograph of a Merehead Quarry diaboleite posted on Mindat that I think is pretty good for the locale because it is terminated. I am also quite fond of chloroxiphite, and one of my sillier notions for a brief moment was to specialize my collecting activities in that one species, figuring that I would be one of the few chloroxiphite specialists.

To answer your question as to whether the grains depicted in "magenta-red 5 download" are typical of the red unknowns that started off this thread, the answer is no. Upon reflection, there are about four distinctions between the red grains. The first crystal and the one entitled "Cranberry-red download 7" are different in hue, with "Cranberry-red download 7" being more red and less transparent. The grains in "magenta-red 5 download" look more like "Cranberry-red download 7" than they look like first crystal also. Finally, there is another bright red irregular group I have been trying to get a photograph of, without satisfactory results. "Odd red 12. jpg" is the best image I have been able to capture. FOV, about 0.4 mm. This grain is unlike the others. One unexpected development, though, in the same area was a purplish red crystal. Again, an unsatisfactory photograph. "Magenta detail.jpg" has a FOV of about 0.2 mm, and is associated with the green botryoidal and a dark minute sphere. The dark sphere actually is intriguing and I will look for more of them, since melanotekite was reported from the Mammoth Saint Anthony Mine as dark radially fibrous balls in diaboleite.

Thus, four different forms/colors. 1) the first crystal is more transluscent and is similar in color to the photograph of Yedlinite depicted in the first edition of the Encyclopedia of Minerals. 2) The photographs of magenta red 5 and cranberry red 5 appear to have similar color and opacity, darker and more opaque than the first crystal. 3) The odd red assemblage is . . .well, odd. This looks amorphous. 4) The final ultra-tiny purple-red crystal.

There are probably enough grains of the first and second category to analyze.

Best regards
Bob Meyer



Edited 1 time(s). Last edit at 08/26/2008 05:21AM by Robert Meyer.

Hello Bob,

I have to agree with Bruce and Joe, the yellow specimen in your recent photo looks like pinalite. I have had a chance to look at a yedlinite with phosgenite and one without phosgenite. The associations are the same. There does not seem to be any leadhillite on these specimens. I think the key to finding a yedlinite is to look for diaboleite associated with wulfenite and dioptase. This association is very rare and so far I have only seen it with yedlinite.

Congratulations on finding the pinalite.

Brent

I had some e-mail correspondence with Bruce Murphy today and he mentioned finding fraipontite from Tiger. I recalled an analysis I had performed on one of my own specimens from Tiger with the same ID, albeit with a trace of Cu. I have attached a photograph of the fraipontite on Mindat and updated the reference for that occurrence to include this analysis. I then recalled on the same piece seeing a very unusual unidentified species in ultra thin blades. The crystals appear almost colorless, except where the light catches one of the tiny edges and modifications, when the green coloration of the 0.3 mm long crystals are apparent. The mineral has a very bright luster and reflects intensely, which causes some distortion in the two attached photographs, but I think you can get the general idea. There are 2 to 3 of these crystals on this specimen. Has anyone seen this material?

Bob

Hi All,

Thanks for posting that purple yedlinite Bruce, that is identical to many of those that I have been observing, on the two new specimens - they even show the same sort of termination. I will see if I can get some pictures done. Bob, sounds like you are going to have some fun working out what those 4(!) different phases are I would keep parkinsonite in there as a possibility.

As for the other phases, again using Merehead as an analogue we've found that melanotekite is always yellowish, but the kentrolite occcurs exactly as you write above in dark (brown-black) radiating balls, has this melanotekite been analysed? perhaps it is kentrolite instead.

I've not seen anything exactly like the last picture, although we have seen some hydrocerussites that can take on a very pale green colour like this from Merehead, but the morphology seems wrong. I have not looked that hard at out Tiger specimens and I'm still learning (thanks to this post) about the Tiger associations! If I get a bit of time one day I'll sit down with a cup of tea and look at more of our Tiger Holdings for the other rarities that may or may not be present.

Out of interest, it would be good for me to know, just how rare yedlinites (and the other rarities) are from tiger, can anyone give me a quick run down on this? maybe a simple list, PM me perhaps. Also are there any "known unknowns" I should be looking out for?

Cheers in advance,

Mike

Hello Bob,

I think your latest photo kind of looks like matlockite with perhaps a little copper to color it green. Speaking of elements coloring species, could it be that chromate is such a strong chromophore that it only takes a few molecules to color something yellow? This would explain why there is no chromium in "chromium leadhillite" or "chromium cerussite". It is also curious that on the material from Tiger that has the "chormium leadhillite", there are abundant amounts of cerussite but none of it is colored yellow. And just to throw something else into the fray, I have attached a few pictures of what I have been calling "green caledonite". These crystals are also associated with the pinalite, and "chromium leadhillite". They occur with normal caledonite and on diaboleite. Is it possible that they contain some chromate to color them green? Or, are these something else altogether?

Brent

Hi Brent,

That green material of yours could be superb Wherryite. However, the form is consistant with caledonite. I analyzed a grain from a crystal similar to those in your photos from the same association and came up with Wherryite. My examples are more deeply colored, though, but not much more so. The presence of chlorine and slightly higher sulfur led to the ID of Wherryite rather than Caledonite. I am questioning that now, seeing your crystals that seem consistant in form with caledonite. I might have to revisit that analysis.

As to the chromium, we took it down to background counts looking for trace impurities. If there is chromium there, it was below the limits of detection of the equipment. Wavelength Dispersive X-Ray Spectroscopy (WDS) was used and that should be able to check down to about 0.2% by weight for chromium. Thus, I don't believe the equipment can detect PPM and the like.

Do you have a lot of material from this paragenesis suite? I find it quite interesting.

Mike,

Answering your question as to what to look for in the collection is difficult. Be careful, or you might end up addicted like me to Tiger material. There are a couple of things to look for, but mainly you will find things you are not sure of. Bideauxite is, in my opinion, the hardest item to find. I have had the chance to closely examine one specimen, but I did not take notes and cannot exactly recall the associates. I do recall that the specimen had boleite and leadhillite present in abundance. Bideaux mentioned another association of species in his article in the Mineralogical Record. Specifically, he mentions an association of boleite and matlockite, which could also be with two generations of leadhillite, sugary anglesite, and cerussite on a matrix of covellite included quartz. I have a number of specimens with this same general paragenesis, and with them a number of unidentified species, but none so far have turned out to be bideauxite. I would closely examine any of your specimens with boleite present.

We have discussed the associated minerals for both yedlinite and pinalite in this discussion thread.

Another tough one would be Mammothite, which would seem to be hard to find among the associated species of anglesite, leadhillite, caledonite, phosgenite, diaboleite, and wulfenite, given that they are cerulean blue in color and small, like many of the species.

To go much further, we might have to start a sort of "Tiger corner" to discuss these minerals.

Cheers,
Bob Meyer

Cheers Bob, and thanks for the info. I'll let you know if I find anything, but don't wait up! I have a lot of other jobs to do first - it was just a passing thought for something fun to do when I have some spare time.

Brent, I've been involved writing some papers on the individual mineralogy of specific areas of the Caldbeck Fells in Cumbria over the past 3 years, where as I am sure you know Caledonite is quite common, in one of them we came across green caledonite very similar in colour to the first of your pictures (Journal of the Russell Society Vol.9 (2006) p.16) Although it was not analysed I expect its true identity to be caledonite and it is of note that there have never been any chromium minerals reported or found at this locality despite an exhaustive search for species, so with that in mind i think it is more likely to be something else rather than trace chromium colouring these examples.

Cheers,

Mike

Hello Bob and Mike,

Bob, I do not think it is wherryite. All the wherryite that I have is usually very light green to almost white and acicular in habit. I have it from three localities, Tiger, Artillery Peak, and the Silver Reef Mountains. The wherryite from the Silver Reef location has much more color but it is still acicular in habit. The pinalite material all came from the Dick Bideaux collection. There were several things on his desk that he was working on when he passed away. All these specimens were put in a flat and sold. I was lucky enough to acquire some of the material a few years ago. There were four specimens that had a sugary quartz matrix with visible diaboleite, caledonite, and leadhillite. It was in these specimens that I was also able to find pinalite, matlockite, cerussite, murdochite, iranite, wulfenite, connellite, phosgenite, the red unknown that I have previously provided a picture of , another green unknown, a blue unknown, and white to light blue acicular needles that were identified as mattheddleite. Both Joe Ruiz and Bruce Murphy have also acquired some of this same material from other collections. Attached is a photo of the other green unknown.

Mike,
It would be interesting to know why a few caledonite crystals will have a distinctive green color and yet they grow along side the caledonite with the typical color. If your ever get a chance to analyze one of the specimens from Caldbeck Fells,I would love to know the results.

Brent

Bob, Brent & Mike:

A couple of brief comments to the last several posts.

Bob: I agree w/ Brent and I believe your pic shows a matlockite crystal; key in that opinion is the high degree of transparency, window-pane habit with edges meeting at 90 degrees and /or with rounded edges. Regarding you questioning your Wherryite ID and example, I have suspected for a long time, which was first brought up by Joe Ruiz, that the morphology looks more like a green variety of Caledonite. Green Caledonite although somewhat rare has been noted on several different Caledonite specimens I have. As luck has it, I just recently found a rich patch of single crystal Wherryites (12-14 of them) and they are decidently different from yours. The Wherryite are extremely clear, glassy, light green, tending to get darker within the crystal and equidimensional w/ rounded sides but a wedge top. Inclusions of Diaboleite and possible Phosgenite are fairly common. Pictures to follow later.

Brent: I believe the first photo of your unknowns looks very much like Caledonite; the second one I am not sure but could be Caledonite; the 3 rd pic looks like a possible Atacamite (?) given its flat top edge, although the color is not a match, and the 4 th pic again an Atacamite-the rounded front is curious as is the color. One additional observation on green Caledonite, I have examples where the transition in color from blue to green is gradual; however on one example, the transition from blue to green is very abrupt, as if two crystals were glued together w/ a sharp color boundary between them. Dana mentions that it can run blueish green and of note is that the streak is greenish-white! Another weird coincidence I just noted checking Dana is that the Caledonite write up is followed on the next page by Wherryite-so in a real sense they are closely related!

Mike: You made my day w/ finding Yedlinites the same as that pic! It gets me to believe that Yedlinite forms several different habits w/ that one the most unusual. Regarding the rarest species from Tiger, Bideauxite is the "hens tooth" and I have only seen one (Dick Thomssen has a killer micro!) followed by Mammothite, then Pinalite.

It would also be interesting to know if some of the specimens you said were received in the 1940's came from Charles Palache, who of course was working up Diaboleite & was drafting up a paper on Tiger itself at the time (see his Gossan Minerals lecture May 5, 1942, to the New Jersey Mineralogical Society transcripts). I am sure close inspection of the museums' Tiger samples will turn up some surprises!

Bruce

Bruce and Brent,

I will have to revisit my analysis of the green mineral. I did detect chlorine, and it was a polished mount, which gave a semi quantitative composition that favored Wherryite. The luster and habit are like Caledonite, though. My other crystals of Wherryite are decidedly different than those, too. The two species are similar in composition, as Bruce points out. In Dana's seventh edition, the two species follow one another, with only the compact fibrous variety of Wherryite being reported. Since the two are similar in composition, I originally thought a transparent crystal of Wherryite might bear some resemblance to Caledonite. Instead, perhaps I should question the analysis. With an EDS analysis, a Pb escape peak coincides with Cl, and the two elements are quite easy to mix up. However, this analysis was performed using WDS, on a machine using six wavelength dispersive X-Ray spectrometers set at different wavelengths. I don't know. I will revisit the analysis.

I have doubts that the thin unknown is matlockite. I had been thinking it was a silicate mineral.

I asked about the minimum detection limit for chromium on the equipment used to do the analysis of the pale yellow leadhillite. WDS is capable of detecting 0.01 percent by weight.

Mike,

I am interested in the mineralogy of Caldbeck Fells, too, and my collection has quite a number of specimens from there, including perhaps 40 specimens of caledonite. Indeed, some of the caledonite does seem to have odd coloration, and some are green, and some are color-zoned. I would be interested in what you are working on and would turn the question around and ask if there is anything I should be looking for. Ha! For grins, I took a quick stab at the attached photograph of a Red Gill caledonite with leadhillite.

Cheers,
Bob

Hi Bob, Bruce and Brent,

Brent, I'll ask around to see if anyone has had a quick peek at the chemistry of the caldbeck caledonites, I suspect someone might. If not I can probably do a very rough and ready EDS analysis sometime in the near future when I'm working on another project.

Bruce, I'm glad the yedlinites I've found interest you - I haven't had the chance to photograph them yet. Will post when I do. We dont have mammothite, pinalite or bideauxite registered in the collections, So I will definitly have a look for these sometime soon. Considering the amount of material we have I'm sure there is something there somewhere. The early suites we have are 1942 from Berman (with Links to Palache) a single 1941 specimen from Mongomery, 1947 from a commercial source and 1957 from Daggett.

Bob, nice picture! The Caldbeck fells are very special to me, its where I first went went collecting as a lad. The area contains alot of different mine sites and localities and each has a different mineralogy - often specimens find their way onto the market as just Caldbeck fells, which makes giving you a list difficult! Some of the very rare minerals from those mines with the Cu/Pb/Zn secondaries include quietite, chenite, elyite, macphersonite, mattheddleite, redgillite, scotlandite, schulenbergite, phillipsbergite & bechererite. Quietite is probably the rarest known, it was found at Red Gill on one specimen that was split into about 10-12 micros.

It would probably be worth your while getting some of the recent editions of the Journal of The Russell Society www.russellsoc.org (Vol.9 (2006) includes reviews of Driggith, Sandbeds, Brae Fell and Arm O'grain Vol.8 No.2 (2005) contains a review of Silver Gill and the upcoming Volume.11 (2008) has reviews of Upper Roughton Gill (Balliway Rigg) and Red Gill.

Cheers,

Mike



Edited 1 time(s). Last edit at 08/28/2008 01:05PM by Mike Rumsey.

Extending the thread a little bit, here's another unknown from Tiger. This occurs with matlockite and boleite, on the tan colored quartz matrix.

The crystal is not large - about 0.1mm long - and has a distinctly bladed appearance, though that's not visible in the image due to the (lack of) depth of field. It's a very dark red-brown with distinctly red internal reflections.

Any ideas what it might be?

Rick

Rick,

I think it could be hematite.

Bob

Hello Rick,

I agree with Bob. It looks like hematite.

Brent