[meteorite-list] Carancas is official

From: bernd.pauli at paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: 07 Jan 2008 20:23:58 UT
Message-ID: <DIIE.000000A200002512_at_paulinet.de>

Matteo wonders:

"H chondrite? ... strange ...similar to ... L chondrite"

Hello Matteo, Jeff G. and List,

That's why I wrote this on Sun Oct 07-2007 with regard to the thin section
pictures you can view here (it was Sterling who posted the link) :

http://www.ingemmet.gob.pe/paginas/pl01_quienes_somos.aspx?opcion=320

"... there is a "conglomerate" of what may have been one or several large BO
chondrules (chondrule fragments). This causes a bit of a headache because,
if this is or was a large BO chondrule, I wouldn't rule out an L chondrite as H
chondrites *tend* to have smaller chondrules!"

But I was careful and wrote "H chondrites *tend* to have smaller chondrules".
One of my Carancas specimens has a beautiful 0.7 mm chondrule protruding
completely from the surrounding matrix - large enough to consider it an L
chondrite. But:

Chondrule size is not the only criterion! These Fa and Fs values below
definitely place Carancas in the realm of the H chondrites:

Olivine (Fa18.4?0.5) and pyroxene (Fs16.1?0.2)

Some examples with (almost) identical Fa and Fs values:

DaG 016 (H5) - DaG 299 (H4) - Dhofar 834 (H4) - Round Top (b) (H4)


Carancasically,

Bernd
Received on Mon 07 Jan 2008 03:23:58 PM PST