[meteorite-list] What's this? -for the geology experts out there

[j.divelbiss at att.net]

Hello fellow green rock picker-uppers. I have more green rocks than Carter has pills. :)

I collect green rocks on a regular basis. After years of collecting and studying, along with the help of fellow green rock collectors like Bob V, I have concluded that my shergonots are related to an area of gabbro/diorite material that has had some of it's plagioclase converted to a green secondary mineral, epidote. These metamorphic gneiss-like rocks are very similar to both Bob's and Graham's rocks.

I once thought all this green stuff was olivine, but several folks have steared me toward the epidote explanation in recent years.

While I am no expert, I do have some of the best green and green-gray rocks around that are strikingly just like shergottites in hand sample.

Green Rocks Rule,

John

  



 -------------- Original message ----------------------
From: Robert Verish <bolidechaser at yahoo.com>
> Hello Brother Graham and List,
> 
> http://marzmeteorite.tripod.com/mars-rocks/2mars1not.jpg
> 
> As you can tell from the above image, Brother Graham
> and I belong to the same fraternity - The Fraternal
> Order of Green Rock Picker-Uppers.
> 
> And here is an "in-situ" image showing where I found
> my green rock:
> 
> http://marzmeteorite.tripod.com/mars-rocks/MRF04996.jpg
> 
> Actually, Graham, my story is much shorter than yours.
> I found my little shergo-not just last week, and only
> a few miles from my backyard.  It was still sitting on
> top of my monitor when I read your message and saw
> your great looking image.  It prompted me to share my
> image with you.  And, as in your image, I placed a
> small slice of DaG 476 in front of my Mars-wannabe. 
> For added effect, I placed a larger slice of the DaG
> 670 stone to the right of my m-wrong.
> 
> As a rule, I don't "hazard a guess" about a rock-type
> based solely on an image.  Too many times I've had to
> change my opinion about a rock-type after examining a
> cut surface.  So, if you show me the inside of your
> rock, I'll show you the inside of my rock!   ;-)
> 
> It's true.  I haven't cut my little rock, yet.  And to
> be truthful, I haven't had it examined by an "expert",
> so I can't say with 100% certainty that my rock is a
> "shergo-not".
> 
> Wouldn't I be emabarassed if I was wrong, and my
> "wrong" wasn't?
> 
> Bob V.
> 
> --------------- Original Message ----------------
> 
>  [meteorite-list] What's this? -for the geology
> experts out there
> Graham Christensen voltage at telus.net 
> Thu Apr 7 05:21:16 EDT 2005 
> 
> 
> Hello list
> 
> I've had this rock sitting on my kitchen table since
> last year when I picked it up along the side of the
> road while out for a walk. It is a fairly smooth 
> green rock with black bits in it and it looks somewhat
> like my DAG 476 
> shergottite but it's a slightly lighter shade of
> green. I have yet to grind an end off to see what the
> inside looks like but there are a couple chips 
> out of it and it looks about the same on the inside
> with the green part being fine grained and the black
> bits are individual crystals. I doubt that it is
> meteoritic (there is no trace of fusion crust) but I
> was wondering if it might be similar to a shergottite
> but of terrestrial origin.
> 
> Here is a pic of it:
> http://www.geocities.com/aerolitehunter/dag476andunidentified.jpg
> The small slice in the forground is my DAG 476 and the
> big rock is of course the rock in question.
> 
> I have been collecting rocks on and off in this area
> since I was a kid and I haven't seen anything like it
> but that doesn't mean much. I live in Alberta, Canada,
> where most of the rocks you find lying on the ground
> were brought down from various locations by the
> glaciers of the last ice age so it's kind of a potluck
> dinner of geology up here.
> 
> I won't get my hopes up, but I certainly wouldn't mind
> copying Bob Verish 
> and finding out I've been sitting on a mars meteorite
> for a year!! :-)
> 
> Any comments are greatly appreciated
> Graham
> 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> 
> 
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