[meteorite-list] Adam's NWA 2989 Acapulcoite

[bernd.pauli at paulinet.de]

Hello John K.,

Thank you very much for the "quick" thin section pictures of Adam's ACAP
and whichever other acapulcoites are more or less probably paired with.

These pics are much more interesting and even more beautiful than all
the talk about assumed or real pairings and TKW's of these acapulcoites!

The low-magnification overview picture is of particular interest because of
the coarser crystals nestled snugly into the smaller crystals that surround
them. Beautiful, equigranular olivine and pyroxene crystals.

Thanks for sharing them!


Hello Mark B.,

Mark wrote that he was surprised at how small the mineral crystals were
in acapulcoites when he got it under his scope at home. But this is not
so very surprising after all.

A very simplified answer may be that crystals in acapulcoites experienced
less heat when they recrystallized (at shallower depths?) whereas lodranites
may have undergone higher temperatures (at greater depths? - where their
crystals also had more time to grow).

References:

McSWEEN H.Y. (1999) Meteorites and Their Parent Planets
(Cambridge University Press, p. 144).

HUTCHISON R. (2004) Meteorites: A Petrologic, Chemical, and Isotopic
Synthesis (Cambridge Planetary Science Series, pp. 250).

FLOSS C. (2000) Complexities on the acapulcoite-lodranite parent
body: Evidence from trace element distributions in silicate minerals
(MAPS 35-5, 2000, pp. 1073-1085).