RE: ASTRONOMY: Dyson redux

From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Wed Jan 08 2003 - 13:19:23 MST


Just a short lesson in cosmochemistry. If my numbers are right,
the ratio of Fe:Li in the sun's protosphere is about 15,800,
the ratio of Fe:Li in the interstellar dust is ~5,500 (varies
from place to place) and in the Earth's crust is ~350.
Interestingly, Li is the 17th most abundant element in sea
water, while Fe is the 23rd most abundant.

Now, I believe that fusion reactions in the sun consume Li, so
that may explain the high ratio there -- but unless the cloud
from which the solar system condensed was heavily enriched over
in Li over the interstellar abundances, it seems likely that Li
will be in short supply in the Kuiper belt.

The increased ratio found in the earth's crust and the ocean can
be explained by the fact that Li is a lithophile (silicate loving)
element and the fact that the crust is mostly composed of silicate
minerals and the fact that Group I elements are relatively easily
ionized and therefore have a relatively high solubility in sea
water.

Bear in mind -- "All that glitters is not gold" -- even if there
are billions of them in the Kuiper belt.

Robert



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