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.
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.


Prepared by:

Randy L. Korotev

Department of Earth and Planetary Sciences
Washington University in St. Louis

Please don't contact me about the meteorite you think you’ve found until you read this and this.