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Post by Ryan on Apr 8, 2011 0:06:53 GMT -5
Found this at the Crabtree last month. Not sure exactly what it is. I was washing it outside and the sunlight caught it and POW. It lit up like a Christmas tree. I took three pics from three different angles with both overhead light, and then directed light to show how glassy and gemmy the crystal is. It didnt look like the "textbook" beryl habit, but what do I know? Id like to hear what some of the more knowlegeable members have to say. I want to get this piece cataloged. I quite like it. Here are some views, hope the pics are good enough to help ID.   |
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Post by lauriesrocks on Apr 8, 2011 9:20:14 GMT -5
yeah, looks like heliodore to me.
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Post by romare on Apr 8, 2011 9:30:26 GMT -5
Appears to be heliodor as Laurie and Rick said.
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Post by Ryan on Apr 8, 2011 14:50:44 GMT -5
Rick, Laurie and Romare agree its beryl, then its beryl.  Or at least thats what the card is gonna say when I put it on the shelf. Is it common for beryl to form with the hex "squashed" like this? Also the little jagged protrusions on the side looked weird. Not like any of the beryl I have collected. What did make me think heliodor was the translucency. Light goes right through this thing. If the crystal were a little more clear, would this be a candidate for a cut? Or maybe a cab? |
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Post by crowsnake on Apr 8, 2011 15:10:12 GMT -5
I'm sure it would make a pretty cabachon.
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Post by ncbbqnut on Apr 8, 2011 15:30:38 GMT -5
Now that I'm home from work I can reply to the post. Ryan, that is a nice specimen you found, and I wanted to throw my two cents into the discussion. I would agree with Laurie, Rick, and Romare 99.9% of the time, but this specimen could actually be something else.
Several years ago Joe (Arappaho) found some crystals at the Crabtree that looked superficially like beryl, but they had a hardness of 8-8.5. Beryl has a hardness of 7.5, so Ryan, you need to do a hardness test on the crystal. If the hardness matches those that Joe found I would say the crystal is probably Chrysoberyl.
I found a specimen of Chrysoberyl at one of the mines near my house in Estatoe in 1966, just a couple of miles north of the Crabtree Emerald Mine. The late Linten Greene identfied it as Chrysoberyl. It was a tabular crystal (not hexagonal) and had the yellow-orange color of golden beryl and fractured look that your specimen has. Chrysoberyl is reported from the Ray Mine, so other beryllium associated pegmatites in the district could have it, too. Check out the Chrysoberyl photos on Mindat.org, especially some of the golden ones from Connecticut......same crystal shape, color and clarity as your specimen.
I was able to examine Joe's specimens under magnification. They were odd crystals and did not entirely fit the crystal structures of Beryl or Chrysoberyl. Another beryllium mineral that is known from the beryl-tourmaline pegmatites in Russia and Madagascar is Rhodizite (hardness 8.5). Rhodizite, a cesium rich beryllium mineral, is only known from one U.S. locality (Wisconsin). It would be incredible to add a new mineral species to NC's list, as well as the Crabtree's. If you and Joe could have specimens analysed to get a positive ID it would solve the mystery of these odd beryllium crystals.
My thoughts above are just speculation, and your specimen may just be an oddball golden beryl, so a hardness test would start the ball rolling on the specimen's identification.
Sometimes, I think too much, but I do like a nice mineral mystery and lively discussion.
Peace,
Dennis
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sophia
Senior Member
Posts: 82
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Post by sophia on Apr 8, 2011 15:33:31 GMT -5
If you want to see if can be cabbed or faceted, you would need to cut it out of host rock, clean it thoroughly, and give it a cook in Opticon. That may seal the fractures enough.
There are many strange beryls at the Crabtree - my husband has found a white beryl with an outer rind of something iridescent blue, like moonstone almost. He's found a white beryl with tiny schorl crystals on it like hair, and beryls that change from green to yellow.
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Post by Dicky the Rockhunter on Apr 8, 2011 17:21:13 GMT -5
I agree with ncmineralman. Could be golden beryl
Dicky
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Post by Ryan on Apr 9, 2011 0:35:37 GMT -5
Dennis, would the Cesium (If Rhodizite) make the specimin radioactive? And if so, radioactive enough to give a reading on my local Fire Depts. Geiger meter?
As for the Chrysoberyl, How exactly would I test for a hardness of 8.5? I have crappy corundum specimins, but they would be too hard, and I have other beryls, but dont want to scratch them up too terribly bad. Maybe Ill go try to scratch a crappy beryl with it... standby...
Ok... I couldnt really tell which one scratched which. The golden specimin appeared to leave a white streak on my piece of Ray mine beryl. But Id say 80% of it wiped away on my finger when I tried to feel for a scratch. It looks like it just barely might have scratched a beryl crystal.
Rick, how big of a piece would be needed to analyze? Or maybe Ill bring it to the next club dig I attend and see what folks have to say. Thanks everybody for their input.
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Post by Ryan on Apr 9, 2011 0:53:46 GMT -5
Wow Dennis, you were so right on about the mindat.org photots. Now Im confused again. lol  |
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Post by ncbbqnut on Apr 9, 2011 8:14:38 GMT -5
Ryan, According to www.webmineral.com, the radioactivity of Rhodozite is barely detectable. The chemical analysis indicated that Rhodizite has 4.3% cesium. Dennis |
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Post by Ryan on Apr 9, 2011 16:21:36 GMT -5
Ah, I see. So no radioactivity test. After viewing the mindat.org photos, Im kind of leaning towards the Chysoberyl for an ID. The shape of the crystal face and the color are what I have to go on now. Im not certian that it couldn't also just be a gemmy heliodor though.
Rick, Im going to attempt to chip a small un-noticeable area of the xl to get the sample grains. I also plan on seeing you guys soon so Ill bring this specimin down for you to have a look at. I have like 5 good specimins that need IDs. MAGMA digs are a great place to ask for help! ;D
Dennis: If you were me, what would be the process you would use to determine the hardness. Also, If I got a porcelain bathroom tile, would there be a difference in streak color between beryl and chrysoberyl?
Laurie: are you going to the Cranberry Dig? If not, Id like to stop by the store soon. If you are going, I may ask you to bring a piece from your store that I might purchase it.
THANKS ALL!!!
Thanks All!
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Post by stairman on Apr 9, 2011 16:49:36 GMT -5
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Post by HeadieRocks on Apr 9, 2011 16:57:20 GMT -5
Ryan, you can purchase kits to determine hardness. I believe they are pretty moderately priced then you always have them handy
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Post by HeadieRocks on Apr 9, 2011 17:04:00 GMT -5
Oh and just a note, there is the possibility that the few small grains run through the machine won't be enough. A few years ago I took a specimen to the ASU geology department for ID. Everybody was floored. They pulled every teacher out of every classsroom in the geology department to see it. Not one had a clue as to what it was. The closest guess was some kind of zeolite. Now, this specimen came out of a VERY old copper mine that I might not should mention, but oh well. It is a tiny pocket of these tabular crystals, white. They broke a few off with my permission to run through the machine for ID, but apparently wasn't enough because they contacted me back wanting more of the crystals, which I was not willing to destroy any more. Here's hoping wherever Rick takes it has better luck that the ASU geology department had with my piece. I had another but didn't even show it to them of these tiny cone shaped crystals with a slight layer of malachite over them coloring them green...
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Post by ncbbqnut on Apr 9, 2011 18:20:42 GMT -5
Ryan,
The hardness kit is a good suggestion. In lieu of a kit, I would use a solid piece of beryl and try to scratch the unknown mineral in an area that would not deface the specimen. I checked the characteristics of both minerals again, and beryl has a hardness of 7.5-8.0 and chrysoberyl is 8.5. Theoretically, beryl should not scratch chrysoberyl.
Both minerals have a white streak, so that test would be inconclusive, and seeing a white streak on a white ceramic tile is difficult.
I think that getting a small sample to Rick for the test at UNC-A is a good idea, and they have identified minerals for Rick before. But Headierocks made a good point. Depending on what type of test is conducted, and by whom, the sample size needed may vary.
Good luck. Who knows what new goodies may be found at the 'Tree?
Dennis
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Post by Barrett on Apr 9, 2011 21:20:16 GMT -5
Try scratching it with a tungsten carbide tool(drill bit or saw-zall blade) if you have one
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Post by arappaho on Apr 9, 2011 23:03:26 GMT -5
Here's a nice garnet from the Tree.   Yes Ryan, that's one of the frustrating things about the Tree. The material is so dinged up or naturally degraded it's hard to tell what it "was". Nice color in your piece. It looks like finding a good surface for a reliable scratch test might be a little tough. Dennis, it was probably the color that made you think of that "mystery" piece of mine, or the fact we were wondering if it might be chrysoberyl, too. But it's the shape of my crystals that makes me wonder what it is. Here's a picture, taken by Scott, of the crystals still in the clump of material I found them in. The best crystal is center top. Another to the right of it and to the left one buried under the garnet-fluid that held much of this piece together.  And I probably should have just left well enough alone, but did I? Needless to say, the specimen don't look like that no more! Sure am glad I have a pic of it. I did manage to recover one almost whole crystal, a partial of another, and a third section I'm not sure about. Here's the almost whole crystal.  A #8 hardness pick will scratch it. #7 will not. It's about 1/4" from tip to tip. The main habit seems to be by-pyramidal with a wide girdle around the center. The next two pics are of one side then the other with light reflecting so you can see the faces better.   The crystal has an S-face, but I don't think this is quartz. Here's a pic of another piece that could be sacrificed in the name of science. Even tho this a partial crystal you should be able to make out the diamond shape with a big girdle.   And last and least, there was this little area I wonder about.  I'm trying to recall how many times I've found quartz crystals, or even druzy, at the Tree? Can't think of any? Be happy to donate to science, Rick. Joe |
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Post by quailriver on Apr 10, 2011 1:53:48 GMT -5
I agree with NC mineralman that Ryan's specimen looks like beryl. Since Joe's crystal has a hardness between 7-8 and looking at the crystal structure I'm wondering if it could be topaz? I know Topaz has been found in a pegmatite rock in Alamance County, NC but I don't know if they it has been found around Mitchell County or not.
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Post by ncbbqnut on Apr 10, 2011 8:11:31 GMT -5
Joe,
It was the color and shape that made me think that Ryan's specimen might be chrysoberyl. I threw out the Rhodizite possiblity because of your specimens and crystal shape after I had the chance to see them in person. The hardness test that you ran on your specimens indicates that they are probably not chrysoberyl or rhodizite (both 8.5). But, it would still be nice to have an expendable piece analysed for a positive ID.
Ryan's specimen may just be golden beryl. And, it may be topaz as suggested. Topaz (hardness 8) is not known from the pegmatites of western NC, but they are found in similar pegs in New England and VA.
It is very difficult to identify many specimens from photographs, and if a specimen does not "look right" to me I try to think outside the rox (rocks), so to speak. By doing so it makes me think and keep my brain churning to find an answer. Also, it makes for lively discussion on this board.
If we all agreed that Ryan's specimen was just golden beryl the thread would be over. No need to try and find out if it is something different or new to the state. Collecting minerals and discovering new things is fun. Let's keeping thinking, discussing, and promoting NC mineralogy.
Sorry for the ramble.
Dennis
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Post by lauriesrocks on Apr 10, 2011 8:39:44 GMT -5
Ryan, I will not be at the Cranberry dig. Come on over to the shop if you can, or I could ship anything to you. Good luck at Cranberry!
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Post by lauriesrocks on Apr 10, 2011 8:47:44 GMT -5
I think Topaz would be out of the question, particularly for the environment where it was found. Topaz in NC occurs in the high temperature, high aluminum deposits of the Carolina Slate Belt, in association with pyrophyllite, andalusite, kyanite, etc. I do not think it would occur in the type of pegmatite found at the Crabtree Mine. Also the crystal form does not look like topaz to me. Joe's pics look a lot like the crystal form of crysoberyl to me. Thanks, Dennis for keeping us on our toes!
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Post by quailriver on Apr 10, 2011 14:45:04 GMT -5
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Post by quailriver on Apr 10, 2011 14:49:34 GMT -5
The color in the photos is showing much paler than in person but the flatter, tabular crystal structure can still be seen
Best Regards,
Larry
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Post by arappaho on Apr 10, 2011 21:18:26 GMT -5
Yes, thanks for the pics Larry. The shape of my crystal is why I couldn't settle on chrysoberyl. I haven't given up on Rhodizite yet. Mindat lists the hardness for Rhodizite at 8, and it looks like a lot of the specimens pictured from pegmatites in Madagascar, for example; www.mindat.org/photo-286839.htmlAnd my piece from the Tree also had the layer, or matrix, of what looks like "melted" garnet surrounding the crystals that many of the specimens from Madagascar also exhibit. Joe |
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Post by quailriver on Apr 10, 2011 23:45:21 GMT -5
Joe, That does look much the same as your specimen. That would be really cool if it is Rhodizite! I'm going to have to dig out my old 1970s collected Crabtree materials and give them a closer look.
Best Regards,
Larry
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Post by lauriesrocks on Apr 11, 2011 7:42:31 GMT -5
Larry, those are great specimens. I have never found any crysoberyl at Snow Camp, way to go! But I would hugely disagree that the Snow Camp deposits are pegmatites. They are hydrothermal metasedimentary and metavolcanic deposits. Pegmatites are essentially combinations of quartz, mica and feldspar, nothing like the Snow Camp or Slate Belt deposits. The Spruce Pine Alaskite intrusives are igneous, while the Piedmont deposits are metamorphic. The reason topaz in NC is commonly found in the slate belt deposits is the presence of volatiles, such as fluorine. Fluorocilicates like topaz need flourine, which is largely absent in the Spruce Pine pegmatites, but since fluorite has been reported from the Crabtree, it could not be ruled out. Certainly topaz can and does occur in pegmatites, in fact the best in the world are from pegmatites, but all pegmatites are not created equal. Another possibility could be Phenakite, a simple beryllium silicate. The chemistry would be right, and the crystal form looks possible. It has a hardness of 7.5 to 8. One way to tell between topaz and phenakite would be the cleavage. Topaz has perfect basal cleavage, so broken surfaces would be smooth planes. Phenakite has uneven fracturing, like the pieces you have found. We might also consider that Joe's and Ryans specimens might not be the same mineral. The mystery continues.
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Post by lauriesrocks on Apr 11, 2011 9:05:12 GMT -5
Another thing has just occurred to me, can't believe I didn't think of it before. This would be in reference to Joe's specimen, which has crystals growing within a miarolitic cavity. This indicates that the crystals are a secondary mineral, formed in a cavity at the latest stage of crystallization of the magma. You will notice that all the emeralds, and likewise all the beryls, regardless of color, are primary minerals that formed completely within the enclosing magma at an earlier stage of crystallization than the open miarolitic cavities. The volatiles that would contribute to the formation of the exotic minerals such as topaz would be the last thing to crystallize out of the magma (late stage crystallization). In other words, heliodore would have crystallized at the same time as the emeralds, and would thus also be completely surrounded by the enclosing pegmatite. It would not form in a miarolitic cavity as is exemplified in Joe's specimen. Therefore I think we can definitively rule out heliodore as Joe's mineral. I am more and more convinced that Joe's and Ryan's specimens are of a different mineral.
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Post by Ryan on Apr 11, 2011 15:18:29 GMT -5
The mystery deepens... I wanted to say topaz for Joes specimin, even though topaz has an orthorhombic habit with pyramidal terminations, could it (Joe's) be a squat little deformed crystal? I like Dennis' reasoning. Lets rule out what it "could" be before just settling on what it "probably" is. Something about my piece just isn't saying "beryl" to me. As for my little crystal, the beryl I was finding that day was all in one little area. I realize they are well worked spoil piles but the pile I was in had similar rocks and very similar beryls. They were all the pale green-yellow completly opaque (well formed) hexes and most of them were quite long. Then out pops this little squat, translucent, LEMON yellow crystal. I want to believe it is not beryl simply because the color is so bright and deep yellow. I have golden beryl specimins but they all have a slight greenish or brownish "mustardy" tinge to them. This piece looks like a shard of a lemon lollypop. Im going to go take a few extreme close-up pics and try to shoot a few images through my jewelers loupe. Maybe an experienced eye will spot a tell-take striation, or fracture, or some other feature indicative of beryl / crysoberyl / topaz / rhodozite / other. Ill post them later. Off to the photo lab! |
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Post by Ryan on Apr 12, 2011 1:03:18 GMT -5
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Or at least thats what the card is gonna say when I put it on the shelf. Is it common for beryl to form with the hex "squashed" like this? Also the little jagged protrusions on the side looked weird. Not like any of the beryl I have collected. 
