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Etch Pattern in Vaca Muerta

Hello List members,

Recently I obtained a 4gm specimen of Vaca Muerta.  I know I'll get my
hand slapped for this, but after polishing the cut side, I couldn't
resist the urge to etch the mostly metallic surface.  Lo and behold,
what had formed was a microscopic etch (Widmanstatten?) pattern!
(see attachments)
Questions:
Can anything be inferred from this very fine pattern regarding metallic
nickel concentration (ataxites?), or does that not apply to
stony-irons(mesosiderites)? 

Were an iron meteoroid to remelt, say by impact with another meteoroid,
wouldn't the resolidified metal have a finer crystal pattern, more as a
result of a comparatively quicker rate of solidification and less as a
result of Fe-Ni composition?  Would there be a pattern at all?

Could etch pattern types in stony-irons be diagnostic for determining
mantle-derived versus impact-derived parent melt?

Hoping my questions make some sense, 
Bob Verish

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