Why this rock is probably not a meteorite:
This rock was sent to us by an gentleman from Missouri who
said that it fell from the sky and that it was still warm when his
father dug it up about a hundred years ago.
The rock has a couple of features that are consistent with a meteorite.
The specific gravity is 3.5, in the range
of ordinary chondrites. It's moderately magnetic.
On the sawn surface (below) there are a few blebs of metal
(not visible in the photograph).
The rock does not have a fusion crust,
however. There are no smooth surfaces, it doesn't have an aerodynamic
shape, and there are no regmaglypts.
We would expect all these features on a freshly fallen meteorite
of
this size. The surface looks weathered, a feature inconsistent with
a freshly fallen meteorite.
On the sawn face (lower photo), the rock is fine grained, perhaps
glassy; there are no visible crystals. There are small vesicles. Chondrites
did not form from crystallization of a melt and, consequently, they
don't have vesicles,
but most do contain visible mineral grains. There is also a line
of
yellowish, rounded blebs that look like "immiscible melt"
consisting consisting of some sulfide mineral. (Chondrules don't
occur in aligned like this, and the don't have vesicles.) Finally,
although
there are some metal grains visible, their abundance is far less
than 1%, which is too low for chondrites.
Coincidentally, this rock arrived a few weeks after we received no.
177; both rocks were found in Franklin County, Missouri.
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What is it?
To us, this "rock" has all the features of some kind of
man-made material - slag from a iron smelting operation. It was found
in an area of the Ozarks where small "mom-and-pop" iron
smelters existed in the 1800's.
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