[meteorite-list] Regmaglypts

From: abudka at nycap.rr.com <abudka_at_meteoritecentral.com>
Date: Thu, 28 Jan 2010 8:44:36 -0500
Message-ID: <20100128134436.6FNET.333736.root_at_cdptpa-web15-z02>

Steve and Everyone,

Steve, Thank you! You are definitely on the right track as far as my thought experiment is concerned!

I have the following comments: in microgravity, there is no density difference between materials because density, as a material property, depends on gravity. So, the concepts of "heavy" and "light" don't apply. My insights into gravity as a variable (The AHA! Moment) came from Springwater pallasite - a light material, olivine, surrounded by a heavy material, nickel-iron.

I am careful not to mention the word "gas" because meteorites are supposed to have been "outgassed."

Steve: "metals or other material with a higher melting point acting as the thin soap skin of the bubble."
Phyllis: Yes for concept of "soap skin" BUT just the reverse for the melting (or solidification) point.

Think solidification of a pallasite such as Springwater. On cooling / solidification, materials with higher melting points will form before those with lower melting points. Olivine begins to solidify before nickel-iron. They share a temperature range where neither is completely solid. On further cooling, olivine becomes solid while nickel iron is not yet completely solid. Iron-sulfur (troilite) will be among the last of the complex melt to solidify. Of course, there are many other compounds that solidify along the way, depending on the overall melt composition.

In such a chemically complex system, the concept of "local composition" becomes important. This implies that there are small differences in solidification points and differences in local surface energy. For additional info, see my "Stepping Back in Time" article on my website, referenced earlier. Another AHA! Moment for me.

Phyllis Budka
http://meteormetals.com/
Received on Thu 28 Jan 2010 08:44:36 AM PST