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Fakes & FraudsStaurolite?

1st Sep 2013 18:45 UTCOlav Revheim Manager

A few years back, light brown ground staurolites allegedly from Fairy Stone State Park, Virginia, USA was available on the market. Does anyone know whether they actually were ground staurolite to "improve" the crystals or just plain fakes?

Please see attached link for photo and more info.

Just ground or also manufactured?

Thanks

Olav

1st Sep 2013 21:00 UTCDenny Lawing

I have collected there and they are real. Found a lot of the crosses.

They do ground them down to improve the cross.

1st Sep 2013 21:07 UTCReiner Mielke Expert

As far as I am concerned a ground down crystal is a fake.

2nd Sep 2013 00:14 UTCDenny Lawing

I do agree with Reiner.

2nd Sep 2013 01:21 UTCEd Clopton 🌟 Expert

I have seen many fake "fairy crosses" that clearly are carved from something like soapstone, including one that sold for a good price on a reputable online auction in the last few years. They make cheap and popular souvenirs, but they aren't mineral specimens.

2nd Sep 2013 18:02 UTCKelly Nash 🌟 Expert

I know there are fakes around, but if you just ask the question about a locality: "are they ground down or are they fake"?, I really think you are ignoring the possibility that some may have just been cleaned of the micaceous matrix with a water gun or some other method. I've done it myself, and they often come out very sharp and with the diagonal striations that are natural - not too unlike the picture you link to. I don't think it is always as easy to know as you might think.

2nd Sep 2013 20:40 UTCOlav Revheim Manager

Staurolite

Fairy Stone State Park, Patrick County, Virginia, USA

Thank you all for sharing your experience with me. I really appreciate that your input :-)

I addition to this thread, I have been in direct contact with Bill Cordua who posted the photo in my original post. . He considers the light brown perfectly shaped staurolite cross in this photo to be not only ground, but also not staurolite. He originally acquired it to be able to show the difference between real and fake staurolite, and apparently there were some of these on the market a few years back.

Mr Cordua posted his photo as a justification to question whether this photo really was staurolite:

this staurolite cross is known to be ground ( see photo caption).

Judged by the appearance of these two specimens,they may come form the same batch of material that was on the market a few years back, and it would really be good if it was possible to find out if anyone had any information on these ground and possible faked staurolite

:-S

The natural specimens that are just water gunned may be very similar, like this one

Staurolite

Picuris District, Taos County, New Mexico, USA

which of course complicates matters. :-)

Again, thank you very much for your input

Olav

2nd Sep 2013 22:22 UTCBill Cordua 🌟 Manager

Here's a photo of a staurolite I bought at Tucson and mixed in with some I collected at Royalton, MN. I used these for years to show my students that some minerals are faked and sold. The staurolite wannabe here was too soft, too low in density and had those funny air holes, which I thought were not likely in a mineral dug from a metamorphic environment. The second picture Olav just submitted looks like bona fide staurolite to me - this chip marks reveal what look like fresh staurolite. The first photo he shows has the odd air pockets I associate with stauro-wrongs. That's why I called it into question - it was jarring in a gallery of really stunningly great staurolite specimens.

3rd Sep 2013 00:05 UTCReiner Mielke Expert

I don't buy the water gun only argument. Striations have to be parallel or perpendicular to some crystal edge, which edge are the staurolite striations parallel or perpendicular to? Also if these are natural striations why don't you see such striations on untwinned crystals? Furthermore Goldschmidt shows no such striations on any of his drawings and if such a thing existed he would have shown it.

3rd Sep 2013 00:56 UTCA. A. Faller

The better quality Staurolite crystals in Virginia are usually found around the Altavista area. They are dark brown, but singles.

The "crosses' around the Fairy Stone Park area, or near the town of Bassett for example, tend to be highly weathered and

yellowish-tan to light brown in color. The actual plus signs tend to be far fewer than various penetration angles, and way to

small for anyone to "cut and shape." I know of no company or lapidarist that collects enough of these from ANYWHERE (as

perfect crosses that are dark brown) in order to mount a peg in to sell as jewelry. I challenge those distributors of these "things"

that claim they are natural to step us through the process, from collection to processing. The presented jewelry is not natural...

3rd Sep 2013 05:16 UTCDoug Daniels

Those "air holes" - they could be where small garnet crystals were located, then removed by either weathering or mechanical means. Garnets are known to occur with staurolites.

3rd Sep 2013 05:39 UTCD Mike Reinke

Of the 2 photos in Olav's post, the top one certainly has a "machined' look to it, far too smooth, consistent, to be natural. If there are numerous sellers of this sort, or one seller with a fair inventory of these, all the more suspect. Any attached garnets would certainly interfere w/ mass production. But if you like your quartz polished, you can have as many of these as you can afford, also.

Mike

3rd Sep 2013 15:25 UTCKelly Nash 🌟 Expert

As Reiner says, the presence or absence of the striations might help answer the question. I recalled seeing these on some twins from Taos County, New Mexico that I cleaned with a water gun - I'll see if I can dig them up and check for striations, my memory isn't perfect.

The second picture in Olav's post above is a twin from Taos County that was supposedly cleaned with a water gun. There are several staurolites in the gallery from various localities showing these diagonal striations, which appear to be parallel to a sphenoidal ("chisel") face on the termination (that is often not present). There are many more pictured staurolite crystals that do not have the striations. But of those that do, some of them don't look like they've been scrubbed. Sometimes the striations are very subtle. I agree I'd feel better about it if Goldschmidt had illustrated them.

3rd Sep 2013 17:51 UTCReiner Mielke Expert

How do you explain the odd angles of these striations? They should be parallel. A closeup of the striations should reveal if they are crystal faces or just grooves caused by grinding.

3rd Sep 2013 21:34 UTCKelly Nash 🌟 Expert

I can't really see that on each crystal the lines are not parallel, though admittedly they are not parallel across the twin contact. I'm not sure they would be exactly parallel in that case, because the crystals are not at an exact 90 degree orientation (I'm thinking it's like 90.5).

I can't vouch for that crystal, I was just saying I don't believe the fact that there are diagonal striations (parallel to the r-face or <101>, I believe) means that a particular crystal has been "shaped".

4th Sep 2013 16:40 UTCKelly Nash 🌟 Expert

I don' t mean to beat this subject to death, but this thread caused me to look closely (with a microscope) at a specimen of mine from Patrick County, VA that I'd posted to the gallery (photo 257830, copied below). Indeed I did find tiny grooves on parts of the surface that indicated the twin has been worked. But the grooves are wavy and cut across the preexisting diagonal striations on the faces, which are really more color bands than grooves, and can especially be seen on the faces at 2:00 and 7:00 in the photo. Interesting as well is that these striations in the lower left quadrant are non-parallel across the twin contact, and look similar to the closeup photo that Reiner posted.

4th Sep 2013 18:46 UTCRob Woodside 🌟 Manager

Kelly, Why is the matrix of that specimen rounded? It is certainly not a river cobble, It looks worked and if the matrix is ground down, why not a little cosmetic grinding on the Staurolite?

4th Sep 2013 18:59 UTCKelly Nash 🌟 Expert

I don't know, Rob. It could have been ground too (I did say the staurolite was reworked). I suppose the whole thing could be a fake, fraud, or abomination of some kind.

But I do think it's staurolite, and I kind of like it.

4th Sep 2013 19:07 UTCRob Woodside 🌟 Manager

That's really all that matters.:-)

4th Sep 2013 19:09 UTCSpencer Ivan Mather

Any ground staurolite wouldn't make it into my collection, nor any other crystal that is enhanced in any other way..

Spencer.

4th Sep 2013 19:09 UTCKelly Nash 🌟 Expert

By the way, Olav's post on "Best Minerals - Staurolite" does show a couple of untwinned staurolites with diagonal striations. Here is one (from France):

4th Sep 2013 19:21 UTCKelly Nash 🌟 Expert

Spencer, I think everybody draws that line differently. Some people have told me that removing a specimen from the outcrop destroys it's value, and brushing off dirt bothers other people (scientifically valuable alteration minerals may have been thoughtlessly disposed).

A water spray gun seems OK for most, how about if I rub it with a stick? A brass brush? Cut and polish a variscite or agate nodule? If I'd thought this one was created with a carving tool, I probably wouldn't have spent the few dollars it cost me, but I think it's largely natural.

I'm pretty confident that 99% of the specimens in my collection have had no reworking other than trimming and cleaning (uh oh), but I personally don't go off the rails about minor alterations (which to me are down the scale from "fakes, frauds, and marketing ploys"). Life's too short.

4th Sep 2013 20:05 UTCOlav Revheim Manager

Thank you all for making this subject a lot more interesting than I thought it would be from the start.

I placed the thread in this forum as the original question was whether an admittedly ground staurolite specimen was in deed staurolite or perhaps another material altogether. The discussion has developed in another, more interesting direction, and I am glad it has. The question now seems to be whether diagonal striations on staurolite crystals can occur naturally ( which it seems it can) and if so, what are the mechanisms causing these striations?

I am afraid that an answer to that is way out of my league.

Thanks again :-)

Olav

5th Sep 2013 02:10 UTCReiner Mielke Expert

Hello Kelly,

Very interesting! But are the striations on both faces? It is difficult to tell from the photo.

5th Sep 2013 02:23 UTCAlfredo Petrov Manager

I share some of Reiner's suspicions. I'm no expert on staurolite, having collected them myself in quantity only in Bolivia and Connecticut, but I don't recall ever seeing clear sharp striations on them, not even very crude ones like those in the picture Kelly put up above. In fact staurolite faces rarely seem to be very smooth and flat, and most frequently show pits and roughness where mica, quartz or garnets were in contact with or partly embedded in the staurolite faces. If I saw a shop with a quantity of staurolites with nice flat faces and showing striations, I'd be suspicious, to say the least, while not excluding the possibility that Nature could actually makes such things in localities I'm not familiar with.

Addendum: Looking carefully at the few photos that appear to show crude striations, I wonder whether those "striations" are due to the crystal structure of the staurolite or whether they are contacts between the staurolite and the planar structure of the enclosing mica?

5th Sep 2013 02:34 UTCKelly Nash 🌟 Expert

It looks to me like the striations are also on the upper face, making chevrons, but it is indeed hard to see. I have been looking around some for a mention of these in the literature, to no avail. American Mineralogist has numerous articles on staurolite crystallography, but nothing I've found shows a hand specimen or talks about the striations. And as Olav says, most of the discussion is out of my league. If I was to speculate (which usually gets me in trouble) I'd say these are related to metamorphic stresses.

5th Sep 2013 02:36 UTCDoug Daniels

I can see the "striations" on both faces of the crystal posted by Kelley. The difficulty seeing them on the upper, well-lit face has to do with the lighting direction. Then again, I'm a geophysicist by training; the old oil-field joke about us is, "what do you want to see, and where?"

5th Sep 2013 03:02 UTCKelly Nash 🌟 Expert

Ha, me too. I spent a couple years looking for lineaments on airphotos and now see them everywhere. Alfredo does raise a possibility. Staurolite crystals, and other metamorphic minerals, often grow in a preferred orientation in the host rock, and I suppose it's possible these striations are a relic of that.

(On edit:) The striations also look a bit like etch pits. Staurolite is quite resistant to weathering/etching, but perhaps there are some situations where there is some etching parallel to the pinacoid (101). I have not really found any decisive reference to a crystallographic explanation for these features, but maybe I just haven't looked hard enough.

5th Sep 2013 19:26 UTCRob Woodside 🌟 Manager

I think the chevrons are too regular to be contacts. This is the first I've seen with these striations and I suspect a grinding wheel.

6th Sep 2013 03:59 UTCKelly Nash 🌟 Expert

Funny how they are doing it all around the world, so carefully, and at the same angle. It really is a vast conspiracy.

6th Sep 2013 06:56 UTCOlav Revheim Manager

I found this article that might explain the oriented pitting in the French specimen included in Kelly'spost at the top of this page.

Olav

6th Sep 2013 07:10 UTCRob Woodside 🌟 Manager

Kelly, you sound like me!!! I don't think they are contacts. My first thought was an abrasion as these are mostly ground out of matrix, but etch pits seem plausible. Their regularity is surprising and they don't appear to respect the orthorhombic symmetry, but then at low temp where the etch pits would form, as the article says, it is monoclinic

6th Sep 2013 13:35 UTCKelly Nash 🌟 Expert

Thanks much for bearing with me, guys, and the reference, Olav. I think there's a fairly small, but significant, percentage of staurolites that show these markings (parallel diagonal lines or etch pits on the prism faces), and there's some percentage of these that are man-made.... That article is a great summary of weathering features. On a quick read, it doesn't call out these particular diagonal features (the weathering pits noted in the paper are largely parallel to the b-face, it seems) but the weathering mechanism, and relation to crystallography is very well explained. I wonder if in-situ, diagenetic alterations form similar etch pits as does weathering on the surface..... I was thinking about my experience with lineament analysis on airphotos, and remembering the "pervasive orthogonal grid" that a couple professors mentioned to me. It's the observed predominance of NW-SE and NE-SW trending faults on the earth's surface. Googling that phrase gets me nothing just now, but I accepted it as a given after looking at a large number of airphotos.

6th Sep 2013 14:28 UTCMark Heintzelman 🌟 Expert

I must admit, the "smoothest" non-pitted or roughly overgrown surface I've ever encountered on Staurolite xtls were on the nicer specimens from Cooks Road in Windham, Maine, which have sharp flat surfaces and a decent luster, or the small single xtls (a few with twining) in chloritic schist from the occurrences near Chestnut Hill, NE of Philadelphia, Pennsylvania. These xtls are also smooth and flat, but with a matte finnish, almost microgranular in appearance, but neither exhibit any sign of naturally expressed nor growth interference striations on them.

Any "natural" specimen I ever saw from fairystone in Virginia had a granular appearance to the surface, NO striations. The locality is best known for the frequency of good 90 degree twining. Very popular as tourist trinkets/curiosities, I remember as a child the one my mother had, a very nice "cross" at a perfect 90 degrees, and she had no particular interest in rocks!

The picture sure looks like the result of grinding to me too.

MRH

9th Sep 2013 19:41 UTCBill Cordua 🌟 Manager

I’ve investigated further the properties of the questionable staurolite twin I bought. It has a hardness of less than 2, is easily carvable by a knife blade, has a specific gravity of about 2.5, and a refractive index of around 1.59. None of these properties match staurolite. From the photo you can see how easy it carved with a knife blade, revealing a much paler color underneath. If natural, it is at best a pseudomorph after staurolite. If so, though, it is hard to see how it survived the cleaning and weathering process. I think it’s a carved composite of some sort, stained on the exterior to resemble the real thing. My 18th edition of Dana’s Manual of Mineralogy by C. S. Hurlbut says (page 387) “most of the crosses offered for sale are imitations carved from fine-grained rock and dyed”. I think that’s the case here. Fortunately I bought this to show my students that minerals sold are sometimes faked. Caveat emptor.

9th Sep 2013 20:46 UTCOlav Revheim Manager

Bill,

Thank you very much!! Do you think that you can upload the two photos you have with the fakes to the database in the "other" category? I would like to use them in the "Best of Staurolite" thread as examples of fakes.

Olav

10th Sep 2013 03:47 UTCBill Cordua 🌟 Manager

Be glad to - just as soon as I figure out how to do it. You're talking to a virtual caveman here. Bill

11th Sep 2013 15:03 UTCOlav Revheim Manager

Faking staurolite crosses seems to be a well known process in Virginia for about 100 years, see Staurolite article all the way to the bottom, in the Virginia section.

Bill, I just noticed that you had uploaded your photos of the fake specimen. I will add them to the article tomorrow.

Thanks

Olav

11th Sep 2013 16:57 UTCVandall Thomas King Manager

Worthy of beating to death. The notches of the twin intersections are rounded.

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