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Newbie needs help from diamond prospectors, Haven't been able to find someone to positively identify
TheRookie
post Aug 8 2015, 07:07 PM
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Okay, to start off with, this is my first post, here. I'm not from Colorado, and neither are the minerals I'm asking for help with. I hope that's not a rules violation. To make a long story short I was doing some gold prospecting in NE Illinois. Yes, Illinois. In with my black sands, which turned out to have some gold, but not enough to mess with, I found these:

Attached Image


After doing a little research, they look to be pyrope, I think. Let me know if you disagree.

Then I found a few rocks like this:


Attached Image


So, I extracted a bunch of the small crystals. Which look like this:


Attached Image


A lot of them still have a bit of the host rock still stuck to them, but, as is, I did a Specific Gravity test and came up with between 3.1 and 3.2 with less than lab-grade equipment. I'm working on cleaning them up some more & when completed in a day or so, will redo my SG test. I also did check the SG of the host rock and that came back at 2.5. My guess is that the cleaning will raise SG to 3.5, or so. The way I did my SG test was to weigh out a sample, then put them into a graduated cylinder half full of water to see how much water was displaced. Using water I had a bit of a problem with air bubbles that just were a bear to get rid of. Would it be better to use a light oil when I rerun my test? I've also subjected them to scratch tests up to mohs 8 (beryl). I don't have any corundum to check further, unfortunately. I've also soaked them in strong, hot acids, and also in lye, none of which has any affect on them. The only thing I've done that had an adverse affect was to heat a couple of them over an open, natural gas flame, 'til they were red-hot, which turned them an opaque white. I've taken these to jewelry shops, rock shops, and a lapidary museum. So far, no one has been able to positively identify these crystals.


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ASTROBLEME
post Aug 8 2015, 09:55 PM
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Hello Rookie,

Illinois could have glacial drift diamonds. The garnets in your photo do look like they could be from a diamond producing formation, however, the crystals you have don't appear to have an adamantine luster like diamond would exhibit. From the specific gravity results, they are too far away from a 3.52 value needed for diamond. The matrix doesn't look like any known diamond bearing rock I've seen and it would have been worn away if subjected to glacial drift actions.

My best guess is that you have collected some fine examples of Phenakite crystals. Phenakite is a fairly rare beryllium orthosilicate with a hardness of 7.5 to 8 and a specific gravity of 2.97 to 3.00. It is infusible and is not attacked by acids.

Search the forum for the topic "Finds from an outing today" by LBC970. That post had a photo of crystals very similar to yours.

You are doing everything right in collecting method, testing and asking for advice. If you have a diamond encrusted tool (Dremel type bur or cut-off wheel) it should easily scratch the crystals by only using hand pressure, without power turning the tool, if they are Phenakite.

Of course these or only my opinions developed from photos... so keep seeking advice and testing until you are sure that the crystals are not diamonds.


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TheRookie
post Aug 9 2015, 03:34 AM
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QUOTE (ASTROBLEME @ Aug 9 2015, 12:55 AM) *
Hello Rookie, Illinois could have glacial drift diamonds. The garnets in your photo do look like they could be from a diamond producing formation, however, the crystals you have don't appear to have an adamantine luster like diamond would exhibit. From the specific gravity results, they are too far away from a 3.52 value needed for diamond. The matrix doesn't look like any known diamond bearing rock I've seen and it would have been worn away if subjected to glacial drift actions. My best guess is that you have collected some fine examples of Phenakite crystals. Phenakite is a fairly rare beryllium orthosilicate with a hardness of 7.5 to 8 and a specific gravity of 2.97 to 3.00. It is infusible and is not attacked by acids. Search the forum for the topic "Finds from an outing today" by LBC970. That post had a photo of crystals very similar to yours. You are doing everything right in collecting method, testing and asking for advice. If you have a diamond encrusted tool (Dremel type bur or cut-off wheel) it should easily scratch the crystals by only using hand pressure, without power turning the tool, if they are Phenakite. Of course these or only my opinions developed from photos... so keep seeking advice and testing until you are sure that the crystals are not diamonds.


Thanks for the reply, ASTROBLEME. There is a little known lamprophyre diatreme about 30-35 miles northeast of where I've been getting this material, in Kenosha, WI, called the Six Pack Lamprophyre. I've got moraines to the east and north.

Several people have said they believe the rock is an "igneous breccia" or as one guy put it, a volcanic rock.

Also, I'm not convinced, at this point, that my SG results are accurate. Will be testing again soon. I also now have a larger sample. Should reduce the margin of error, I hope. Do you think light oil will eliminate my air bubble problem?

As far as a diamond dremel bit, no it doesn't scratch them very easily with just hand pressure. I've actually been using one to pick away at & clean up some of the larger crystals a little.

Wish I could get better photos for you, a really good camera isn't in the budget at this point. 'Til it is I just gotta make do with my cell phone and a cheap tabletop magnifier.
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ASTROBLEME
post Aug 9 2015, 10:32 AM
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TheRookie,

If you have some larger crystals, I'd advise checking them with an electronic diamond tester. Most pawn shops have them so perhaps you can get a quick test on the larger specimens.

Sounds like you are in a good area to prospect for diamonds. Good luck!


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"Some day this crater is going to be a greatly talked about place, and if the above credit is due, as is certainly the case, I would like to have it generally known for the sake of the children." Daniel Moreau Barringer 2/1/1912 in a letter about the Barringer Meteorite Crater, Arizona USA
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TheRookie
post Aug 9 2015, 03:12 PM
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QUOTE (ASTROBLEME @ Aug 9 2015, 01:32 PM) *
TheRookie, If you have some larger crystals, I'd advise checking them with an electronic diamond tester. Most pawn shops have them so perhaps you can get a quick test on the larger specimens. Sounds like you are in a good area to prospect for diamonds. Good luck!





I actually just extracted a stone that's about 1 1/2 ct. the other night. That's by far the largest one so far. Up 'til then the largest stones were about 1/2 ct. I've heard that diamond testers can give a false negative reading if the stone is held between your fingers, is that true? Because I took one to a pawn shop and a jewelry store that tested one of them that way.

It's funny that you say that it sounds like a good area to prospect, most people think I'm crazy as a bedbug. I've heard and read that drift diamonds in the Midwest all came from Canada, but I wonder how much truth there is in that. The accounts I've read about a lot of the diamonds found in the area describe many of them as being "off color". For example, the documented diamond finds in Indiana include diamonds that were "pinkish, blue, pink, brownish yellow, greenish yellow, and between white and yellow". Aren't Canadian diamonds known for being mostly colorless? BTW, many of mine, if they turn out to be diamonds, are not colorless.
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ASTROBLEME
post Aug 9 2015, 05:53 PM
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TheRookie,

I don't know about how holding the target stone would affect the reading on diamond testers so I won't venture an opinion other than you're thinking the right way in trying to solve the puzzle. Keep up the effort until you know what the crystals are for sure.

There is a meteorite impact crater near Coloma WI that is not well studied. The original impact may have cratered with a diameter in excess of 13 miles but the present surface trace is only about 5 miles in diameter. This means that lots of erosion has occurred and that size of crater can bring diamonds to the surface. I've been called crazy for proposing the relationship between diamond deposits and large impact craters but the experts are moving more and more towards my way of thinking. There is a multi-ring dike structure that I think is an impact near my diamond finds. I'm pretty sure the structure is an ancient crater but I don't have access to the central core area where evidence would most likely still remain. Anyway, something had to trigger an emplacement of numerous kimberlite pipes in the vicinity and cratering is the most likely event at Stateline Mining District.

Do you know the direction of the glacial drift from the Glover Bluff Crater? If the drift is towards your prospects, then that would explain the indicator garnets and would be a good place to search for diamonds in my opinion. Let em' think your crazy... that will keep the crowds down!


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Tonko Mining Company

"Some day this crater is going to be a greatly talked about place, and if the above credit is due, as is certainly the case, I would like to have it generally known for the sake of the children." Daniel Moreau Barringer 2/1/1912 in a letter about the Barringer Meteorite Crater, Arizona USA
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TheRookie
post Aug 9 2015, 07:40 PM
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QUOTE (ASTROBLEME @ Aug 9 2015, 08:53 PM) *
TheRookie, I don't know about how holding the target stone would affect the reading on diamond testers so I won't venture an opinion other than you're thinking the right way in trying to solve the puzzle. Keep up the effort until you know what the crystals are for sure. There is a meteorite impact crater near Coloma WI that is not well studied. The original impact may have cratered with a diameter in excess of 13 miles but the present surface trace is only about 5 miles in diameter. This means that lots of erosion has occurred and that size of crater can bring diamonds to the surface. I've been called crazy for proposing the relationship between diamond deposits and large impact craters but the experts are moving more and more towards my way of thinking. There is a multi-ring dike structure that I think is an impact near my diamond finds. I'm pretty sure the structure is an ancient crater but I don't have access to the central core area where evidence would most likely still remain. Anyway, something had to trigger an emplacement of numerous kimberlite pipes in the vicinity and cratering is the most likely event at Stateline Mining District. Do you know the direction of the glacial drift from the Glover Bluff Crater? If the drift is towards your prospects, then that would explain the indicator garnets and would be a good place to search for diamonds in my opinion. Let em' think your crazy... that will keep the crowds down!


As far as I can tell, from the maps I've looked at (and I'm no expert) Glacial drift from Glover Bluff Crater would've ended up a bit west of me. As to people thinking I'm crazy, if these are diamonds, after I have enough of them, I'll be eccentric.

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Denise
post Aug 10 2015, 07:25 AM
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Welcome to the CP forums TheRookie. Make yourself at home around the site, we have several threads that could also be helpful to you.
Some great questions and no worries, no rule violations here. It looks like Astrobleme has given you some great info. He would definitely be the man to talk to about Diamonds. thumbsupsmileyanim.gif cool.gif

Good luck out there and stay safe. We would love to hear how it turns out.


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TheRookie
post Aug 10 2015, 07:58 AM
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QUOTE (Mrs.CP @ Aug 10 2015, 10:25 AM) *
Welcome to the CP forums TheRookie. Make yourself at home around the site, we have several threads that could also be helpful to you. Some great questions and no worries, no rule violations here. It looks like Astrobleme has given you some great info. He would definitely be the man to talk to about Diamonds. thumbsupsmileyanim.gif cool.gif Good luck out there and stay safe. We would love to hear how it turns out.





Thank you. I've been lurking, on and off, for a while now. Have perused some of those other threads, was hoping for feedback from Astrobleme, and a few others, actually. If anyone has any tips, suggestions, whatever, I'm pretty open. So far, I've only screened a couple yards of sand/gravel, & found about 2 lbs. of the reddish colored rock above. As of right now, I have around 12 grams of the crystals extracted. What I haven't broken up looks like it contains about 6-8 more grams. Depending on what they turn out to be, I've got 50-75 more yards of material to go through. The larger gravel is going in my driveway, the smaller gravel on a separate pile, in case it warrants further processing. Large rocks will be used for landscaping. The sand, I'll use to break up the hard clay soil we have around here. The hole that will be left will get lined & filled with water, for a small goldfish/irrigation pond. If nothing else, I have my own, personal, gravel pit, right in my backyard.

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TheRookie
post Aug 12 2015, 12:38 PM
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Some of the small ones after soaking for a couple days in Whink rust remover:

Attached Image








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Diamond Digger
post Aug 14 2015, 06:19 AM
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Hi,
First picture is garnets but not Pyrope G10 that you will need to have diamonds present.
I also do not see any diamonds in the pile of white stones you have there. The usual tell tales are missing. Triangles, oily shine on the surface etc.
DD
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TheRookie
post Aug 14 2015, 07:12 AM
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QUOTE (Diamond Digger @ Aug 14 2015, 09:19 AM) *
Hi, First picture is garnets but not Pyrope G10 that you will need to have diamonds present. I also do not see any diamonds in the pile of white stones you have there. The usual tell tales are missing. Triangles, oily shine on the surface etc. DD


Thanks for the reply, DD. I've come to the conclusion that these are probably not diamonds. Just have no idea what they are. I finally was able to get a bunch cleaned up enough to redo my SG calculation and, as long as my calculations are correct, The SG is too low to be diamond. They're closer to quartz' SG, but, scratch tests so far have shown them to be quite a bit harder than quartz. They also have been able to withstand several other tests that should have destroyed, or seriously degraded, quartz. Their crystal habit is also not suggestive of quartz. The larger singles I've been able to extract whole appear to be octahedral in shape. Some do have triangles on their faces, some raised, some recessed. It's just very difficult to get them to show up in pics taken with a cheap phone and an even cheaper desktop magnifier.

As far as G10 pyropes, there were none identified during the exploration of the diatreme near here, though there were pyrope garnets ranging in color from purple through red, and orange, as well as "numerous small diamonds". The only report I've been able to locate can be found here: http://www.d.umn.edu/prc/lakesuperiorgeolo..._Sudbury.CV.pdf

pages 11-12 (overall, they're the 43rd & 44th pages of the document)


Second page, first paragraph, last sentence of the report:
QUOTE
No subcalcic "G10" varieties have been identified.











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Kim Shaffer GG
post Nov 14 2015, 07:06 PM
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I just happened upon this discussion in the process of searching for information on a related subject. I am a GIA trained Graduate Gemologist and I have a low tech suggestion to offer that I believe would be helpful.

Select one of the smaller specimens and smash it with a hammer. (Wear goggles and do this inside a box that will keep the fragments from flying everywhere.)

Due to its cleavage, diamonds break with a characteristic step-like fracture. Many other minerals cleave, but I have never seen any that break with the same appearance as diamond.

If the material breaks with a conchoidal (shell-like) fracture, such as glass does, the material is not diamond.

So this simple test has the potential of providing a definite negative, but not a conclusive positive.

The triangular markings on diamond crystals are called trigons. If those are present, that is a good indication. If you have some small specimens you would like me to examine for you, I would be happy to.

Best Regards,
(Mr.) Kim Shaffer, G.G.
Wichita, Kansas
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MikeS
post Nov 15 2015, 10:56 AM
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QUOTE (Kim Shaffer GG @ Nov 14 2015, 07:06 PM) *
I just happened upon this discussion in the process of searching for information on a related subject. I am a GIA trained Graduate Gemologist and I have a low tech suggestion to offer that I believe would be helpful.

Select one of the smaller specimens and smash it with a hammer. (Wear goggles and do this inside a box that will keep the fragments from flying everywhere.)

Due to its cleavage, diamonds break with a characteristic step-like fracture. Many other minerals cleave, but I have never seen any that break with the same appearance as diamond.

If the material breaks with a conchoidal (shell-like) fracture, such as glass does, the material is not diamond.

So this simple test has the potential of providing a definite negative, but not a conclusive positive.

The triangular markings on diamond crystals are called trigons. If those are present, that is a good indication. If you have some small specimens you would like me to examine for you, I would be happy to.

Best Regards,
(Mr.) Kim Shaffer, G.G.
Wichita, Kansas


Welcome to the forums Kim! thumbsupsmileyanim.gif
Thank you for the useful tips. I have not prospected for diamonds yet, but I hope to give it a try next season.


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Kim Shaffer GG
post Nov 15 2015, 11:43 AM
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QUOTE (MikeS @ Nov 15 2015, 11:56 AM) *
Welcome to the forums Kim! thumbsupsmileyanim.gif
Thank you for the useful tips. I have not prospected for diamonds yet, but I hope to give it a try next season.


I hope to, as well. I have been investigating areas where it appears alluvial prospects might be available for prospecting.
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