[meteorite-list] Conception Junction approved (question)

From: MexicoDoug <mexicodoug_at_meteoritecentral.com>
Date: Sun, 28 Aug 2011 13:54:21 -0400
Message-ID: <8CE33C2A65B6E36-14A4-3E6F8_at_webmail-d140.sysops.aol.com>

Hi Carl,

Yes, mg/g is milligrams per gram and ?g/g is micrograms per gram.

thus, 6.0 mg/g is 0.6% or 6 ppt (parts per thousand, the analog of
percent but based on one-thousandths)

and, 24 ?g/g is 0.0024% or 24 ppm (parts per million, the analog of
percent but based on one million)

and If none of the other Pallasites show data that way it is probably
because they were published before measurements of trace metals was
seen as an important classification tool (at least, in the opinion of
Wasson et al). Wasson published a huge paper/review with many tables
on the subject comparing many irons and arguing that trace metals are a
good classification tool. I am still amazed he has had as good results
as he presents, since meteorites are natural materials and variations
among traces doesn't seem unlikely, though I am sure others will view
the mixing as more uniform (but - if everything was so uniform, for
example why do we have more olivines in some slices, or areas of many
inclusions, etc, ok ... seeding for crystals an imperfections is a
different concept but still ... enough of my monologue - I( am sure he
has run many duplicate runs using different sampled sections of
material from the same meteorites and found that on balance perhaps
even if one metal is off, they can be relatively independent variables
- at least some of the metal concwentrations, relative to each other
and are useful in separation. Not an easy sell or an easy job, I would
have gone bananas with such a project if I had such a monumental task
to deal with in a lab. You really got to give him credit. But I still
bet there are some nuances in this classification system that will need
to be worked out due to the base assumptions of mixing. They will
probably be attacked by ratios and appropriately selecting metal
element pairs or subgroups.

Oh wait, of the 20 US pallasites, the one published to Concepcion
Junction was Milton, also of Missouri, in 2000:
http://www.lpi.usra.edu/meteor/metbull.php?code=16691
you will notice it is the latest one - same format:

Milton
Found 2000 October
Pallasite
A single mass of 2040 g was found in a bean field by Ben Rogers and
Gary Wennihan. Initial identification was made by C. Rohs and J. Reese
at Northwest Missouri State University. Classification and mineralogy
(R. Jones, UNM; J. Wasson, UCLA): Small, angular olivines (73 vol%),
mean Fa17.2; molar Fe/Mn = 123; metal composition, Ni = 151 mg/g, Co,
9.6 mg/g, Ga, 15.3 ?g/g; As, 10.1 ?g/g; Ir, 50.4 ?g/g, Au, 1.16 ?g/g.

Kindest wishers
Doug


-----Original Message-----
From: cdtucson at cox.net
To: meteorite-list at meteoritecentral.com
<meteorite-list at meteoritecentral.com>; Laurence Garvie <lgarvie at cox.net>
Sent: Sun, Aug 28, 2011 11:32 am
Subject: Re: [meteorite-list] Conception Junction approved (question)


Laurence,
Sorry if this is a stupid question but none of the other pallasites in
the
bulletin show their data this same way.
looking at this data . What does it mean when it says;
mg/g etc...
Is this milligrams divided by grams?
What would the percentage be put in a way that it can be compared with
the way
others are reported?

Geochemistry: Compositional data: Co 6.0 mg/g; Ni 79 mg/g; Ga 24 ?g/g;
Ge ~80
?g/g; As 29 ?g/g; Ir 0.50 ?g/g; Au 2.39 ?g/g. Data are the mean of
duplicate
determinations. The composition of the metal differs in detail from
other
pallasites. For example, the Ir concentration is 0.50 ug/g, with the
nearest
relative Seymchan at 0.67 ?g/g and Barcis at 0.32 ?g/g.
Classification: On element-Au diagrams, Conception Junction plots
distinctly
lower than most PMG on Ni and Cu and above most PMG on Co, Ga, As, and
Ir
diagrams; it is therefore classified as PMG-anomalous (PMG-an). Its Ni
and Cu
contents are the lowest known for PMG. Its nearest PMG-an neighbor on
most
diagrams is Krasnojarsk. The low Ni and high Co could reflect
unrepresentative
sampling of kamacite and taenite but these are the means of two
replicates.

Thank you.
Carl
meteoritemax







---- Laurence Garvie <lgarvie at cox.net> wrote:
> For those that are interested, Conception Junction was approved today.
>
> see
> www.lpi.usra.edu/meteor/metbull.php?code=53877
>
> Laurence
> CMS
> ASU
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Received on Sun 28 Aug 2011 01:54:21 PM PDT