[meteorite-list] Olivine, Quartz, and Enstatite... was Slump glass

From: STARSANDSCOPES at aol.com <STARSANDSCOPES_at_meteoritecentral.com>
Date: Mon, 9 Feb 2009 09:23:46 EST
Message-ID: <d62.2b178e65.36c19672_at_aol.com>

Well said Elton! Thanks

Tom

In a message dated 2/8/2009 11:40:07 P.M. Mountain Standard Time,
mstreman53 at yahoo.com writes:

Good Question: "What about Olivine, would the melt point of Olivine be
higher than the glass?"

Molten olivine at "silica glass" melting(aka"fusion")temperatures.

Not at all as olivine has the highest fusion temperature in Bowen's Reaction
Series(BRS). Thus it is the first to crystalize and precipitate out of
magma. This is why it is used as a refactory material in making fire bricks.
Olivine fuses at 1890*C, well above where iron fuses. The two minerals making up
olivine: forsterite and fayalite are very close in fusion temperatures as to
be negligible in general discussion.

Silica, aka "quartz" has the lowest fusion temperature in BRS(1600*C +) and
thusly rare in meteorites. That fact and this:When olivine is forced to react
with quartz in any of several situations such as reheating,deep mantle
pressures,extended cooling cycles,etc., the two minerals reform to produce
enstatite. (Does the H and E chondrite composition and their parent bodies make more
sense?)

When this quality of olivine and it's implications sink in, one might
experience the "Eureka" effect. It goes very, very far in explaining why meteorite
petrology is the way it is:Especially, pallasites.

Elton

**************A Good Credit Score is 700 or Above. See yours in just 2 easy
steps!
(http://pr.atwola.com/promoclk/100000075x1218550342x1201216770/aol?redir=http://www.freecreditreport.com/pm/default.aspx?sc=668072%26hmpgID=62%26bcd=fe
bemailfooterNO62)
Received on Mon 09 Feb 2009 09:23:46 AM PST