[meteorite-list] Chassigny "Chondrules"

From: bernd.pauli_at_paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: Thu Apr 22 10:21:09 2004
Message-ID: <DIIE.0000005B00000D68_at_paulinet.de>

J=C9R=C9MINE E. et al. (1962) Etude min=E9ralogique
et structurale de la m=E9t=E9orite de Chassigny
(Bull. de la Soc. Fr. de Min=E9ralogie et de Cristallographie, LXXXV, pp. 262-266)

Dans les plaques minces que nous poss=E9dons, nous avons pu observer un ph=E9nom=E8ne
curieux et suggestif. Il se localise dans l'olivine sous la forme d'une enclave aux contours
arrondis ou ovo=EFdes, tr=E8s nettement d=E9limit=E9s provoquant comme dans le cas du min=E9ral
opaque, un d=E9veloppement des fissures radiales sugg=E9rant une augmentation de volume
par croissance. Cette formation est compos=E9e principalement d'hypersth=E8ne, en cristaux
allong=E9s, l=E9g=E8rement tordus, s'adaptant aux contours externes ovo=EFdes. Un peu de feldspath
comble de tr=E8s petits espaces interstitiels (on y aper=E7oit de fines aiguilles de pyrox=E8ne). Il
existe en outre un mince anneau ayant une orientation optique unique, plus bir=E9fringent que
l'hypersth=E8ne de la partie centrale (probablement du diopside). Nous avons l=E0 une =E9bauche
parfaite d'un petit chondre (polysomatique).

Translation (by Bernd Pauli):

In the thin sections that we have at our disposal, we could observe a strange, suggestive
phenomenon. It is to be found in the olivine and forms an enclave with rounded or ovoid
contours which are clearly delineated and promote the development of radial fissures
(just like in the case of the opaque mineral). This is suggestive of an increase of size by
growth. This inclusion is dominantly composed of elongated hypersthene crystals which
are slightly twisted and which follow the external, ovoid contours of the rim. Small amounts
of feldspar fill very small interstitial spaces (fine pyroxene needles can be seen in these
areas). There is also a thing ring showing a unique optical orientation, more birefringent
than the hypersthene of the central part (probably diopside). This is a perfect preliminary
form of a small (polysomatic) chondrule.

Oh world of chondrules,
thou art bewildrering !!

Bernd
Received on Mon 28 Jul 2003 11:40:01 AM PDT