[meteorite-list] L, H what?

From: bernd.pauli_at_paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: Thu Apr 22 10:31:10 2004
Message-ID: <DIIE.0000003900001DB3_at_paulinet.de>

Hello Tom and List,

Yes, lab testing will probably be the only sure method to classify
a meteorite unambiguously. My NWA 984 (LL4) slice has lots of
easily visible FeNi metal specks, my Saint-Severin (LL6) has lots
of FeNi specks (large and small), my Parnallee (LL3.6) is choke-full
of metallic iron. Same thing with my Tenham (L6) or my Suizhou (L6).

So "high iron" and "low iron" does not primarily refer to the visible amount
of nickel iron in the matrix. Table 3.3 in D.W. Sears (1978) The Nature and
Origin of Meteorites (Adam Hilger Ltd, Bristol), p. 62 has some interesting
details:

Principal minerals in chondritic meteorites (wt%) for types 5 and 6:

Olivine H => 33-37 / Pyroxene => 23-27 / Kamacite (FeNi) => 15-17
Olivine L => 45-49 / Pyroxene => 21-25 / Kamacite (FeNi) => 06-08
Olivine LL => 56-60 / Pyroxene => 14-18 / Kamacite (FeNi) => 01-02

In words:

The amount of olivine increases, the amount of pyroxene decreases
as you go from H => L => LL.

But:

The total amount of the low-nickel kamacite decreases from H => L => LL
as more and more iron is "oxidized" that is: needed for the silicates.

Best wishes,

Bernd
Received on Sat 03 Apr 2004 12:57:16 PM PST