[meteorite-list] Primitive Achondrite Question

From: MexicoDoug <mexicodoug_at_meteoritecentral.com>
Date: Tue, 6 Dec 2011 11:33:23 -0500 (EST)
Message-ID: <8CE824BE7F5701E-1CE0-11F4B_at_webmail-m043.sysops.aol.com>

Dr. Grossman wrote:

"Some PACs do in fact contain relict chondrules, especially
acapulcoites and winonaites."

Thanks. Now I appreciate how the relict condrules being "cosmic" or
"terrestrial" in nature can throw a wrench into the classification
scheme, especially for highly weathered meteorites where conceivably
the classifier is presented with what s/he must decide could be the
remnant of both in series and use whatever vestiges they can.
Classification scientists have enriched the world so much that they've
far outgrown their breeches ;-)

If 'primitive achondrite' or 'metachondrite' is just an attempt to add
a gray area between black and white (chondrite vs. achondrite) the idea
sounds great, and looks a lot a geological micro-version of the "great
planet debate". So, an achondrite hasn't necessarily "cleared it
chondrules" ;-) ... ! Very philosophical to a layperson or even an
enthusiast. No wonder you enjoy CO's and CV's so much. I can't wait
until someone turns up a CV6+. Theoretically, there is no reason to
bar the possibility,, or is there...

Kindest wishes
SDoug



-----Original Message-----
From: Jeff Grossman <jngrossman at gmail.com>
To: meteorite-list <meteorite-list at meteoritecentral.com>
Sent: Tue, Dec 6, 2011 7:38 am
Subject: Re: [meteorite-list] Primitive Achondrite Question


  Some PACs do in fact contain relict chondrules, especially
acapulcoites and winonaites.

Some chondrites have no chondrules (CIs and highly altered ones, plus
some type 6 and 7) and some PACs do. Life is not always simple!

Jeff

On 12/5/2011 9:22 PM, MexicoDoug wrote:
> There are relict chondrules identifyable in LL7's according to the
> definition I read, though if you dig through David Weir's or Dr.
> Bunch's websites you will probably get updated information.
>
> So, it can't be an achondrite, primitive or not. If anything it
would
> have to be a "highly evolved" chondrite; --- same logic we just saw
> with Al Haggounia 001 not being an aubrite = chondrule .. not an
aubrite
>
> but in that Al Haggounia case, chondrules that were not completely
> mineralized with replacements are present, and Greg Hupe has an
> unambiguous chondrule that he kindly shared with me that is extremely
> well defined (dropping it to a "3" in that case assuming not 100%
> relict).
>
> What happens when a chondrite is just past the metamorphic stage that
> chondrules are no longer identifyable is probably a variable process
> causing confusion among classifications of sparcely occuring
> chondrules in 6's and those of 7's. Must be a bit to come up with
> uniform criteria since nature has her own sometimes cryptic ways. It
> would only get interesting if different parts of the same rock get
> baked in a non-uniform oven.
>
> Kindest wishes
> Doug
>
>
> -----Original Message-----
> From: Ruben Garcia <mrmeteorite at gmail.com>
> To: Meteorite List <meteorite-list at meteoritecentral.com>
> Sent: Mon, Dec 5, 2011 8:23 pm
> Subject: [meteorite-list] Primitive Achondrite Question
>
>
> Hi all,
>
> I just bought a smallish collection and several of the slices that
> came with are NWA 3100. Mike Farmer's card was included and lists NWA
> 3100 as an LL7. The Met-Bul calls NWA 3100 a Primitive achondrite -
> not an LL7.
>
> My question is this,
>
> Does LL7 denote a particular Primitive achondrite? If so which one? If
> not then what type is this?
>
> BTW - I think Ted Bunch did the classification
>
> --
> Rock On!
>
> Ruben Garcia
>
> Website: http://www.mr-meteorite.net
> Articles: http://www.meteorite.com/blog/
> Videos: http://www.youtube.com/profile?user=meteorfright#p/u
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Received on Tue 06 Dec 2011 11:33:23 AM PST