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 <[email protected]>
To: meteorite-list <[email protected]>
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 <[email protected]>
To: Meteorite List <[email protected]>
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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