[meteorite-list] A good read on converting standard microscopes to polarizing-chondrule formation

From: starsandscopes at aol.com <starsandscopes_at_meteoritecentral.com>
Date: Sun, 17 Jan 2010 23:46:02 EST
Message-ID: <25a54.58253358.3885418a_at_aol.com>

Hi list, Not a typo, one article that covers such things as conversion of
a standard bright field microscope to polarization, various lighting
techniques, as well as chondrule formation.

A little slow in parts but then again, this isn't HBO!

An example to persuade you to take a look or cause you to hit your delete
key so fast it's left with fusion crust.

"The "classic" barred olivine texture is a single plate dendrite
(Donaldson, 1976) which shares the entire chondrule with the remaining glass or
subsequent crystallization products. Olivine rimming the chondrule is often in
optical continuity with the dendrite and thus is part of the plate
dendrite. Because this texture is so striking, barred olivine (BO) chondrules are
well known even to people outside the field of meteorites. When chondrules
are discussed, a photomicrograph of a barred olivine texture is usually
chosen as one of a few or even the only example. It is not surprising that
considerable effort has been expended understanding its origin. Barred olivine
textures comprise only a few percent of melt-textured chondrules, usually
less than 5% (Gooding and Keil, 1981). The "classic" barred texture
represents only 10% of the type 3 ordinary chondrite BO chondrules. By careful
study, Weisberg (1987) determined that the multiple plate dendrite is a much
more common that the single dendrite. Most investigators propose that BO
chondrules form from melt droplets that crystallize rapidly upon cooling."

Enjoy? but then check out my Meteorite Micrograph Gallery hosted by
Meteorite Times. I employ most of the techniques outlined in this article in my
various image styles.

http://www.meteorite.com/meteorite-gallery/meteorites-alpha_frame.htm

Tom Phillips
Received on Sun 17 Jan 2010 11:46:02 PM PST