[meteorite-list] Never underestimate or dismiss Spectroscopy

From: Benjamin P. Sun <bpsun2009_at_meteoritecentral.com>
Date: Wed, 16 May 2012 20:40:03 -0400
Message-ID: <CAE1PX842HxfG3_dn6=weOh=nOy67r73dwcQDQiFa6_MqOP05vA_at_mail.gmail.com>

"Generally speaking, stating to the HED clan of meteorites are mainly
derived from "Vesta" is acceptable so long as we understand ( Caveat
#1) that they could also be from any of the Vesta family: any of
those 6000+ bodies populating the Vesta orbital region. Many of
those are over 1 km size and most but not all have Vesta matching
spectra/albedos."


I'd consider that the many Vestiods of the Vesta family were and are
still pieces of their parent body, Vesta. Not counting the odd
interloper or co-habitant of the group region, of course.
Just like the many martian and lunar meteoriods(martianiod? lunoid?)
out there floating in space, blasted off their PB's, were and still
are considered pieces of Mars and the Moon respectively.
Speaking for myself, it matters very little whether my HED came from
Vesta directly or indirectly from a Vestiod. In the end, it's still
from Vesta.


"The second caveat is covered elsewhere in recent list commentary: the
fact that we do have some non-Vestian eucrites was panned as
"insignificant". Well, Au contraire-- the existence of a but a
solitary example is proof that the "basaltic, sub/minor-planetary
differentiation process" happened on more than a single body. Adding
credibility to the planetary-science model. Naively stating over
and over that "all eucrites " come from Vesta" won't make it true.
Doing so retards the advancement meteorite science."


Keep in mind that the word "eucrite" and "eucritic" was a rather broad
and loosely used term back in the (old) day(s). Scientists now are
more specific in it's usage, accurate and clear with their
classifications . So some of those old eucrites and rare "non-Vestian
eucrites" need to be re-examined and possibly reclassified.


>From Wikipedia:

"Eucrites are achondritic stony meteorites, many of which originate
from the surface of the asteroid 4 Vesta and as such are part of the
HED meteorite group. They are the most common achondrite group with
well over 100 distinct finds at present.

Eucrites consist of basaltic rock from the crust of 4 Vesta or a
similar parent body. They are mostly composed of Ca-poor pyroxene,
pigeonite, and Ca-rich plagioclase (anorthite)."


I happen to agree with this definition. Also:


"Eucrites get their name from the Greek word eukritos meaning "easily
distinguished". This refers to the silicate minerals in them, which
can be easily distinguished because of their relatively large grain
size.

Eucrite is also a now obsolete term for bytownite-gabbro found on
Earth. The term was used as a rock type name for some of the Paleogene
igneous rocks of Scotland."
Received on Wed 16 May 2012 08:40:03 PM PDT