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Looking for help trying to identify find
Woody
post Oct 29 2012, 08:18 PM
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By chance anyone have a clue as to what this mineral/Rock/Gem might be?

I was out this weekend rooting around in the ground and found a spot where someone long ago had dug for fluorite. I was looking though their debris pile and had found several small, low grade pieces with some purple and green showing. Often when I am out and about I will keep pieces or chunks of smoky quartz, especially if they are deep black, “Ooh Shiny”. So when I picked this piece up that’s what I thought it was smoky quartz. I never would have kept such a small piece, “it is only 1 inch wide and about 1 ½ inches long” but once I picked it up I could tell the fracture was not what one would expect from quartz. I couldn’t bring myself to through it away so I tossed it in my pack knowing I could look at it again after I cleaned it off.

So I got home and was washing all my finds off and got to this one. When I picked it up this time I did not have gloves on and immediately noticed another strange characteristic, it was unusually heavy for its size. After I cleaned it off I could see that although it looked black at first, I believe it is actually an intense red. There is one small spot that is damaged and it shows dark red. Difficult to tell though as light will not pass through it.

Additional info/Re-cap;
1. Intense black and shiny.
2. Does not fracture like quartz. It is uneven and chunky.
3. Does not scratch with good knife or file.
4. Very heavy in weight. I would say it has a specific gravity about that of iron.
5. It is extremely opaque, light will not pass through it even around the edges.
6. Small damaged area shows red.
7. It is associated with decomposing granite on one end and microcline on the other.

That’s about all I got. Any guesses? Woody

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russau
post Oct 30 2012, 06:25 AM
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the black area looks like it maybe somesort of volcanic rock like Obsidian.
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swizz
post Oct 30 2012, 07:05 AM
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I was thinking Obsidian at first too until you described it further.
These three factors: Heavy, won't scratch, and a tinge of red.... have me leaning toward Pyrope Garnet or maybe Peridotite?
Can you do a hardness test? That would really help narrow it down.


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Woody
post Oct 30 2012, 05:20 PM
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I tried doing a hardness test on it but don't have anything readily available for material harder than 6.5, a good steel file will not scratch it so it goes beyond that. I wish I had a simple home test that could measure specific gravity. It is noticeably heavy in hand for such a small piece. Quartz is fairly hard, “7 or so”, but it is not heavy enough. Same thing with obsidian, not heavy enough. Galena seems to have about the same weight as this mineral. I’ve never seen anything from the garnet family up in this area but I would think that garnets are a heavy mineral.

I think I have seen this in some of the rocks I brought home before. I remember a couple of items had a small inclusion that at the time I thought was just a tear drop sized piece of smoky quartz. Looking back I remember that it was absolutely opaque just like this item. By “opaque” I mean I can hold a high power flashlight right up to it and light does not pass. Not even just a little bit on the edges, Just like onyx.

Search continues~


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CP
post Nov 2 2012, 08:23 AM
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Hi Woody,

This is just a stab in the dark basically but knowing kinda what area you are prospecting and things we've found in similar areas.....possibly a sample of rutile?

Another possibility that Mrs. CP thought of.....black tourmaline?

Any streak from the sample? Your comment on reddish edge could suggest some type of garnet?

Good luck on this id, we'll be looking forward to find out what it actually is.


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russau
post Nov 3 2012, 06:33 AM
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take it to the closest colledge in the geology department and ask them for a quick answer.
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theschwartzz
post Dec 27 2012, 05:14 PM
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Looking for assistance to identify geometric chevron shaped inclusions in a Brazilian Amethyst cluster.
It has a plethora of Goethite inclusions (commonly known as Cacoxenite) and a number of these other inclusions that exactly parrot the shape of the Amethyst face that encompasses it.
Therefore some are triangular and some have a flat top mimicking the facet, and they are made up of a profusion of tiny black specs under 20X with spaces in between.
One area has a few that are more solid with one also exhibiting several deep orange areas.

Is this likely to be Lepidocrosite (or Hematite) or another form of the Goethite?
Have a couple of pictures if that would help.

Also is there an easy way to tell Lepidocrosite apart from Brookite when there are only amorphous black shapes present?

Thank you
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swizz
post Dec 27 2012, 05:40 PM
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Hi schwartzz and welcome to CP. sign0016.gif
If you have some pics it would be really helpful... I'd love to see it.
I also have a weird crystal inclusion on a large Amethyst specimen which I've not identified. Would be nice to compare.
Let me know if you need help posting pics.


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theschwartzz
post Dec 29 2012, 08:35 PM
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QUOTE (swizz @ Dec 27 2012, 05:40 PM) *
Hi schwartzz and welcome to CP. sign0016.gif
If you have some pics it would be really helpful... I'd love to see it.
I also have a weird crystal inclusion on a large Amethyst specimen which I've not identified. Would be nice to compare.
Let me know if you need help posting pics.

Apologize for the delayed response - mother-in-law in hospital again.
There about a dozen pictures in total, but none of the really show the facet parroting black speck filled inclusions. Most showcase the Goethite.
However the 2 solid triangles are visible in a pair of images.
Not sure if I did the picture attachments correctly. First image is the entire cluster and the other 2 of the solid triangular forms.


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CP
post Dec 31 2012, 08:52 AM
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Hi Schwartzz,

Hope your mother in law is feeling a bit better now.

Those are great pics of the inclusions, very neat! I do not know of an easy way to tell those differences. The amethyst coloration is caused by the iron inclusions if I remember it right, I've never looked at one this close to see that, or if any I've had in hand over the years had them. very cool!
Let us know what you find out in the end, there are some quartz crystals found here in Colorado that have a brilliant red solid coloration with specks that might be caused by the same inclusions. Be cool to know what's causing that color in the quartz crystals.....and then of course, go find some more of them! Rats! Winter just started..... kick_can.gif Have to wait for spring to get a bit closer. biggrin.gif


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theschwartzz
post Jan 1 2013, 12:36 PM
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QUOTE (ColoradoProspector @ Dec 31 2012, 08:52 AM) *
Hi Schwartzz,

Hope your mother in law is feeling a bit better now.

Those are great pics of the inclusions, very neat! I do not know of an easy way to tell those differences. The amethyst coloration is caused by the iron inclusions if I remember it right, I've never looked at one this close to see that, or if any I've had in hand over the years had them. very cool!
Let us know what you find out in the end, there are some quartz crystals found here in Colorado that have a brilliant red solid coloration with specks that might be caused by the same inclusions. Be cool to know what's causing that color in the quartz crystals.....and then of course, go find some more of them! Rats! Winter just started..... kick_can.gif Have to wait for spring to get a bit closer. biggrin.gif

Happy New Year!!!

Unfortunately she is not doing well and likely will have to go under the scalpel today.
You are correct Iron is the coloring agent in Amethyst. This cluster has darker purple phantoms sprinkled about and none of the parroting phantoms with the black specs showed up well in a picture. I may try to take a picture through the stereoscope. Used a Nikon with a Macro to take these close up images.
I have about 40 Amethyst clusters with Goethite, but have only looked at a handful through the stereoscope.
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Denise
post Jan 8 2013, 08:32 AM
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Sorry to hear your mother in law was still having problems. Hopefully she is doing better now.

I have a 20x loop that I use to check out specimens closer. It's amazing what you see that you didn't before looking through the scope.
We would love to see more pictures of your finds when you have time. Amethyst is beautiful stuff especially with inclusions. Nice finds! thumbsupsmileyanim.gif


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