Can anybody identify this old rock found in tennesee?

Question

This rock or object was found 60+ years ago in a field in Tennesee. It has a black outer coating and what looks like a silvery flakey inside that seems to radiate from the center of the object. There is a small round speck in the middle that looks like a small piece of rust. When I received this object we measured it and it was surprizingly very round and only differed by a few hundreds of an inch on all sides. It had a crack in it and I was told that the gentleman that found it tried to break it open by prying in the crack. So I assumed this object was very hard because it was still in one piece. Wrong ! After showing this to some friends at work we noticed it was begining to crack more, so I decided to break it open. Wow we have no clue what this is. Its like fibers all facing to the center of it. Oh yeah we also tested it under a very powerful metal detector and it did not detect it. Also under a very powerful magnet hanging from thread it did not desturb it at all.

Answer 1

The description you have given sounds exactly like a nodule of macasite (not the stuff you see in jewellery which is either pyrites or cut steel) Marcasite is a dimorph of iron pyrites with the formula FeS2. It often occurs as nodules like you describe as the result of crystals growing from a single starting point and radiating out in all directions forming a ball shape. The dark "skin" is limonite which is hydrated iron oxide and forms over a long period due to the action of weathering. These are very common in the South of England where I come from and have all sorts of fancy names such as "thunderbolts" and "cannon balls" etc. They are interesting as specimens but have almost no commercial value.

Answer 2

i'm not a geologist. i understand meteorites should be heavy, iron or stone varieties, or carbonaceous chondrites, which will be exceptionally mild. Yours do not look all that very resembling assorted the carbonaceous ones you will see that on google pictures, yet there is diverse sorts of this stuff, and they type of resemble a number of them. they don't look into all like the massive, mild business cinders you frequently discover round railroad tracks, that could be my first wager with out the images. Meteorites should be well worth some money. in case you imagine there is any probability it truly is what they're, take them to a geology branch at some community college. you ought to grant a touch leisure for whoever's there if not something else.

Answer 3

You didn't give much info on how large it is, hardness scale, streak or magnetic property. Making a guess I think you have a chunk of glassy dacite that is devitrifying. This is like snow flake obsidian. You could take it to a geology department at any local college or university and they might be able to tell you more about it. It is also might be a meteorite, but doesn't sound like any I have seen. More like a volcanic rock fragement.

Answer 4

I agree with previous answers it would have been nice for more details. But given the little you offered, I am inclined to go with the limonite nodule. No natural obsidian balls in Tenn, but lot of limonite nodules. The rusty hole in the center is very classic.