[meteorite-list] Define shock value

[bernd.pauli at paulinet.de]

Hello Walter, Hi Jeff, Hello List,

In addition to Jeff's informative website that describes Dieter
Stöffler's petrographic shock classification of chondrites, some
more details that help recognize the shock stage when you look at
a thin section of a chondrite under a microscope in plane and/or
polarized light:

STÖFFLER D. et al. (1991) Proposal for a revised petrographic shock
classification of chondrites (Meteoritics 26-4, 1991, A398-A39):

S1 (unshocked) - sharp optical extinction of olivine
S2 (very weakly shocked) - undulatory extinction of olivine
S3 (weakly shocked) - planar fractures in olivine
S4 (moderately shocked) - mosaicism in olivine
S5 (strongly shocked) - isotropization of plagioclase
   (maskelynite) and planar deformation features in olivine
S6 (very strongly shocked) - recrystallization of olivine
   and phase transformations of olivine (ringwoodite)


Cheers,

Bernd