[meteorite-list] How many oriented meteorites?

[Frank Cressy]

Hello All,

Nininger's figures come from his book, "A Photographic
Study of Surface Features - Part II
Orientation".  On page xiv of the Introduction,
Nininger states:  "Orientation appears to be more
prevalent among the nickel-iron variety of meteorites
than among stony meteorites.  A survey of some 7,000
individual meteorite fragments showed 28 percent of
the irons to be oriented, while only 5 percent of the
stones showed evidence of orientation.  This is due to
the greater specific graviety of irons, that results
in their maintaining higher velocities throughout
longer flights than stony meteorites.  Also, because
of their greater strength, iron meteorites may be less
prone to disruption."

Nininger found a high percent of the Estherville Ni-Fe
"pellets" to show orientation features.  I don't know
if he included these in his calculations.

All the best,
Frank


--- Mark Crawford <mark at meteorites.cc> wrote:

> Hey Tim,
> 
> I don't know about 'fully' oriented, but according
> to Norton ~5% of 
> stony meteorites show 'some degree' of orientation,
> and that irons are 
> (helpfully!) 'sometimes' oriented.  He attributes to
> Nininger an 
> estimate that 28% of irons are oriented, but doesn't
> define the degree 
> of orientation.
> 
> Mark
> 
> 
> Tim Heitz wrote:
> > Hello List,
> >
> > How many 85% to 100% oriented meteorites do you
> think are found?
> >
> >
> > 1 in 5000 for an iron meteorite
> >
> > 1 in 500 for a stone meteorite
> >
> > Whats your best guess?
> >
> > Thanks,
> > Tim Heitz
> >
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