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

From: Mr EMan <mstreman53_at_meteoritecentral.com>
Date: Sun, 8 Feb 2009 22:58:59 -0800 (PST)
Message-ID: <359679.1672.qm_at_web55204.mail.re4.yahoo.com>

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
Received on Mon 09 Feb 2009 01:58:59 AM PST