timloco
has rocks in the head
Member since April 2012
Posts: 545
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Post by timloco on Apr 5, 2015 15:30:18 GMT -5
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Fossilman
Cave Dweller 
Member since January 2009
Posts: 20,723 
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Post by Fossilman on Apr 5, 2015 20:27:12 GMT -5
Nice stuff,liking the different ways it shows off itself!!!!!!!!!!!!!!!!!
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Post by snowmom on Apr 6, 2015 5:50:48 GMT -5
Wonderful! those are great, and I think you are spot on! I find it here too and never made the connection!
timloco gets the rock detective gold star. Bet others who posted epidosite photos will 'click' with this post too. (so interesting!)
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Post by nowyo on Apr 6, 2015 8:25:50 GMT -5
Interesting stuff. Just curious as to how you're coming up with the id.
Russ
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timloco
has rocks in the head
Member since April 2012
Posts: 545
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Post by timloco on Apr 6, 2015 8:29:28 GMT -5
The ID is a guess, based on what snowmom has mentioned about epidote and how its chemistry is and the color of it.
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Don
Cave Dweller
He wants you too, Malachi.
Member since December 2009
Posts: 2,616
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Post by Don on Apr 6, 2015 10:15:37 GMT -5
that rock makes me hungry for some reason.
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rockroller
spending too much on rocks
Be excellent to each other.
Member since October 2013
Posts: 359
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Post by rockroller on Apr 6, 2015 17:49:10 GMT -5
The one with the criss-crossing quartz stripes is really Cool!!
~Roland
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timloco
has rocks in the head
Member since April 2012
Posts: 545
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Post by timloco on Apr 7, 2015 16:13:34 GMT -5
So, fwiw I had a email conversation with a local geologist at CSU, and he's guessing jasper. check it out:
Tim:
The epidote-rich rocks people bring me for identification are generally epidote veins cutting the Precambrian granitoids
or metamorphic rocks from the Front Range. These are striking and people notice them especially where the nice
green epidote veins cut the pink granitoids. Piemontite would require very different conditions—a ridiculously Mn-rich
hydrothermal fluid, to create veins of the stuff. I’m no piemontite expert but I suspect one generally needs Mn-rich
(probably metasedimentary) rocks which are then metamorphosed.
You’re exactly right—we’re getting a hand-held XRF, so it would only take a minute or two to (probably) identify
a mineral, assuming it is mono-mineralic. Since it’s H=7, I’ll stick with my guess for now that it’s likely jasper, but again,
we’ll be happy to zap it next summer after the instrument is in-house.
Jerry
Huh, cool! I guessed the piemontite because the same area has tons of epidosite, and some of this stuff looks a lot like the epidosite only red instead of green. It's a 7 for hardness.
There's a lot of brown and tan jasper out there so I'm pretty familiar with that, and some interesting agate. I've got good pictures of the epidosite this stuff looks like.
Let me guess you're getting some kind of x-ray diffraction machine or something like that?
On Tue, Apr 7, 2015 at 1:28 PM
Hi Tim:
Correct, piemontite is rare, and I’m not sure there are any known localities in Colorado. But the rock
does look like it might be deformed, which would likely indicate it came from the mountains. Did you
test for hardness? If you can’t scratch the red stuff with a knife, and in fact leave metal on the rock,
my first guess would be red microcrystalline quartz (essentially jasper).
If you’re interested, by next summer sometime, we should have an instrument for measuring composition,
and this would be a quick way of identifying the material.
Good pictures, by the way—often I’ll get images from folks too fuzzy to tell anything. Yours definitely
look like the rock is deformed, as from an ancient fault zone, and it looks like mostly quartz (all the white
stuff) though there could be feldspar too. The red stuff COULD be something more interesting, like an
economically useful mineral, but we could check that this summer.
Jerry
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Post by snowmom on Apr 7, 2015 17:37:17 GMT -5
Wow Timloco, great info and great that you have a good geologist connection. It really does look like the same stuff in a different color. I hope you take advantage of his offer to zap it and get a reading on it, it would sure help us all pin down what this stuff is. I know there are several of us with what looks like the same stuff on the board here. Thanks for the post! Much appreciated!
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Post by nowyo on Apr 7, 2015 19:44:37 GMT -5
Tim, excellent job on following up on what this stuff is. The whole piemontite thing never did make any sense.
Russ
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rockroller
spending too much on rocks
Be excellent to each other.
Member since October 2013
Posts: 359
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Post by rockroller on Apr 7, 2015 23:47:18 GMT -5
Hey Tim ( timloco), I've been trying to look up more info on piemontite since these discussions started. I found a few pics of some Colorado specimens but the piemontite was in very small crystal formations. It would be awesome if you had access to a XRF machine!! Coincidentally, only a few days ago I met a man from San Antonio, TX who said that his daughter and son-in-law live in Loveland and his son-in-law is a Geology professor at CSU. Really small world it is!! Looking forward to more of your discoveries! ~Roland |
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Post by gingerkid on Apr 8, 2015 10:51:25 GMT -5
So, fwiw I had a email conversation with a local geologist at CSU, and he's guessing jasper. check it out: Tim: ... we’ll be happy to zap it next summer after the instrument is in-house. Jerry LOL! timloco, I can see why your pretty material made Don hungry - some of it looks like bacon. I tried to cab some piemontite from New Mexico for @rocks2dust a while back. The color of it reminded me of almandine, and it undercut pretty badly due to the variation of hardness of the materials in it. Gorgeous stuff, though. |
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Post by gingerkid on Apr 8, 2015 14:08:33 GMT -5
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timloco
has rocks in the head
Member since April 2012
Posts: 545
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Post by timloco on Apr 9, 2015 19:22:19 GMT -5
cool, how hard was the stuff you worked with?
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Post by gingerkid on Apr 10, 2015 11:19:09 GMT -5
timloco, I read that piemontite is around 6 to 6.5 on Mohs, but I'm thinking it may be harder since it's inclusions (?) of piemontite in quartz. I hit it on the 180 grit diamond wheel, 280 grit flex wheel, then used diamond paste on polypads since the material undercuts.
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